Mechanics refers to the grammatical conventions of how words, letters, and typographical symbols are arranged to create logical meaning. Mechanics includes four distinct principles: spelling (the proper order of letters in a word); capitalization and emphasis (the alteration of size, case, or typeface to give an idea more weight); syntax (the arrangement of words into larger logical units of phrases, clauses, sentences, and paragraphs); and punctuation (the addition of symbols before, after, inside, and in between words to clarify meaning).
American English recognizes 12 standard punctuation marks that are necessary for mechanics in formal writing. The period (.), question mark (?), and exclamation point (!) indicate sentence boundaries and the purpose of a sentence. The comma (,) also indicates boundaries and separates syntactic groups. In contrast, the colon (:), semicolon (;), and dash (--) are concatenations that join and separate at the same time. Unlike the dash, the similar-looking hyphen (-) only joins letters and words. The apostrophe (') indicates possession and syncope. Sets of quotation marks, both the dual (" ") and singular (' '), indicate direct speech. Sets of enclosers, which include parentheses () and brackets [], indicate supplementary information. The addition of other common punctuation like the asterisk (*), solidus (/), pesodollar ($), ampersand (&), and octothrope (#) are a matter of usage, which are the accepted conventions allowed by a specific discourse community but not all English language discourse.
American English recognizes 12 standard punctuation marks that are necessary for mechanics in formal writing. The period (.), question mark (?), and exclamation point (!) indicate sentence boundaries and the purpose of a sentence. The comma (,) also indicates boundaries and separates syntactic groups. In contrast, the colon (:), semicolon (;), and dash (--) are concatenations that join and separate at the same time. Unlike the dash, the similar-looking hyphen (-) only joins letters and words. The apostrophe (') indicates possession and syncope. Sets of quotation marks, both the dual (" ") and singular (' '), indicate direct speech. Sets of enclosers, which include parentheses () and brackets [], indicate supplementary information. The addition of other common punctuation like the asterisk (*), solidus (/), pesodollar ($), ampersand (&), and octothrope (#) are a matter of usage, which are the accepted conventions allowed by a specific discourse community but not all English language discourse.
After periods, commas are the most used punctuation mark in the English language. At the same time, commas are the most misused punctuation mark too. Commas are commonly seen as the most difficult of all the punctuation marks to place, and grammar checking software stats show a majority of errors are related to comma use. To be fair to those of us that make these errors, commas seem to do a lot of things and have many rules.
However, commas get a bad rap. They aren't inherently complex, as commas simply do one thing:
However, commas get a bad rap. They aren't inherently complex, as commas simply do one thing:
Commas separate words, phrases, and clauses.
Think of them as the opposite of conjunctions--instead of bringing things together, commas push thing apart. Commas separate items in a list (I bought apples, grenades, and teddy bears). Commas separate two independent ideas that have been tied together (Kelsey likes grammar, but nobody likes Kelsey). Commas separate nonessential information from the rest of the essential words in a sentence (Mike, who likes to wear goth makeup and fishnet sleeves, married my mother).
So if commas only do one thing, why are they so difficult to nail down compared to other punctuation? This comes down to the difference between mechanics and usage. If you skipped reading the box at the top of this page, mechanics are fixed conventions in American English, i.e., this is always the rule. Usage, however, is the function of a specific discourse community, i.e., the rule changes depending on who you're talking to. Specifically, different style guides for writing (MLA, APA, CMOS, AP) have different rules for how language is used.
This isn't too problematic for most punctuation, as their core functions are mechanical while usage only dictates different conventions for atypical situations. Take periods: no matter what the usage guide, periods end declarative and imperative sentences and follow abbreviations. The only real question when it comes to periods is how they are used with initialisms like US/U.S.--MLA and CMOS would say no periods needed while APA and AP would require periods. While style purists may throw a fit if the wrong US is used, both are seen by most people as acceptable.
Commas, however, are different.
So if commas only do one thing, why are they so difficult to nail down compared to other punctuation? This comes down to the difference between mechanics and usage. If you skipped reading the box at the top of this page, mechanics are fixed conventions in American English, i.e., this is always the rule. Usage, however, is the function of a specific discourse community, i.e., the rule changes depending on who you're talking to. Specifically, different style guides for writing (MLA, APA, CMOS, AP) have different rules for how language is used.
This isn't too problematic for most punctuation, as their core functions are mechanical while usage only dictates different conventions for atypical situations. Take periods: no matter what the usage guide, periods end declarative and imperative sentences and follow abbreviations. The only real question when it comes to periods is how they are used with initialisms like US/U.S.--MLA and CMOS would say no periods needed while APA and AP would require periods. While style purists may throw a fit if the wrong US is used, both are seen by most people as acceptable.
Commas, however, are different.
Commas are evenly split between mechanics (always true) and usage (sometimes true).
To get granular, there are twelve types of recognized comma use in English. Half of the conventions are based on mechanics--these six functional commas are necessary for the sentence to maintain logical integrity. The other six stylistic commas follow conventions that shift based on the guidelines of the specific discourse community regarding their usage. This does not mean that stylistic commas are optional--it means that where and how the commas are required can vary.
The following article looks at each comma and the conventions around its use. Like the other articles in Coonwriting, this is based on Modern Language Association (MLA) style, which doesn't really matter for half of the entries... and as for the other half, there will be info for how the usage conventions are different when conforming to American Psychological Association (APA) style, the Chicago Manual of Style (CMOS), and Associated Press (AP) style.*
*While Coonwriting also typically addresses two other popular style guides--the National Library of Medicine (NLM)/Vancouver style and the Institute of Electrical and Electronics Engineers (IEEE) style--both are exactly aligned with the Chicago Manual of Style when it comes to comma usage.
Foundational Commas (Universal)
The following article looks at each comma and the conventions around its use. Like the other articles in Coonwriting, this is based on Modern Language Association (MLA) style, which doesn't really matter for half of the entries... and as for the other half, there will be info for how the usage conventions are different when conforming to American Psychological Association (APA) style, the Chicago Manual of Style (CMOS), and Associated Press (AP) style.*
*While Coonwriting also typically addresses two other popular style guides--the National Library of Medicine (NLM)/Vancouver style and the Institute of Electrical and Electronics Engineers (IEEE) style--both are exactly aligned with the Chicago Manual of Style when it comes to comma usage.
Foundational Commas (Universal)
- The Syndetic Clausal Comma: Joining two independent clauses with a coordinating conjunction ("I wrote, and they read").
- The Parenthetical Comma: Offsetting non-essential, supplemental descriptive info or narrative appositives ("The guide, which was thoroughly researched, was published").
- The Vocative Comma: Isolating elements that modify the entire sentence, including nouns of direct address ("Listen to me, reader"), interjections ("Hey, that was mine"), and conjunctive adverbs ("With that said, she persisted").
- The Attributive Comma: Separating direct speech from the indication of its source ("She said, 'Write clearly'"; The document explicitly warns, "Do not copy this material.").
- The Interrogative Comma: Isolating tag questions at the end of a declarative statement ("This makes sense, right?").
- The Structural Resolution Comma: Separating adjacent words or phrases that would otherwise cause an accidental structural misreading or a rhythmic "stutter" in the reader's brain ("Whatever happens, happens"; "To John, Smith was an absolute hero").
- The Serial Comma: Separating three or more items in a simple list ("apples, oranges[,] and bananas").
- The Coordinate Adjective Comma: Separating reversible, descriptive words modifying the same noun ("a cold, rainy day").
- The Displaced Comma: Marking elements, such as introductory adverbial or concessive clauses and modifying phrases, that have been moved out of their natural order to the head of the sentence ("Although it rained, we walked"; "Grinning from ear to ear, she crossed the finish line").
- The Unit Comma: Separating distinct categorical units in numbers, dates, geography, or professional suffixes ("May 20, 2026," or "John Smith, PhD").
- The Contrast Comma: Separating an idea from its direct, elided opposite ("I asked for sparkling water, not still water").
- The Gapping Comma: Indicating omitted words in a structurally balanced sentence elision ("I ordered coffee; she, tea").
Commas create boundaries by separating elements in a sentence.
Foundational commas are universally used across every variant of English:
- help coordinating conjunctions join two independent clauses (the syndetic comma)
- offset supplemental phrases and clauses to show they are nonessential (the loose comma)
- separating direct speech from the indication of its source (the attributive comma)
- isolate elements that modify the entire sentence (the vocative comma)
- isolate declarative statements from tags that turn them into questions (the interrogative comma)
- split adjacent words or phrases that would otherwise cause a misreading (the resolution comma)
Stylistic commas have different requirements based on community conventions:
- indicate elements that have been moved from their logical spot to the head of the sentence (the reversing comma)
- separate distinct categorical units in numbers, dates, and geography (the unit comma)
- separate three or more items in a simple list (the listing comma)
- separate adjectives that modify the same property of the same noun (the coordinate comma)
- separate an idea from its direct, elided opposite (the antithesis comma)
- indicate elided words in a balanced sentence (the gapping comma)
When to not use commas:
- never combine independent clauses with just a comma without a conjunction (comma splice)
- never move a participle phrase away from the noun it modifies (dangling participle)
- drop excessive commas when they fragment sentence fluency (choppy comma)
- don't add commas to indicate a verbal pause (prosodic comma)
SYNDETIC COMMAS: Friend of the FANBOYS
|
|
Clauses--the basic units of meaning in a sentence--are either independent or dependent. An independent clause (sometimes known as a verb clause) can stand on its own as a complete sentence, whereas a dependent clause cannot.
When writer wants to add more than one clause to a sentence, they need to add a linking element to tie the two clauses together. In a running sentence (i.e., the standard type of sentence construction), the independent clause is followed by a subordinating conjunction and the dependent clause. Instead of joining the independent clause to a dependent clause, what if the writer wants to join it to another independent clause to create a compound sentence? A mechanical convention of English is that, unless a writer is creating a running sentence, clauses can only be combined if there is a linking element and a boundary element to show where one clause ends and another begins. While English has some punctuation called concatenations that can both link and create a boundary, most clause combinations use a conjunction to link and a comma to create a boundary. Two independent clauses can be linked by a coordinating conjunction, AKA the FANBOYS (for, and, nor, but, or, yet, so). When this happens, a comma needs to be added after the last word in the first clause before the coordinating conjunction. Since the joining of two words, phrases, or clauses with a coordinating conjunction is called a syndetic connection in linguistics, the comma that accompanies the coordinating conjunction is called the syndetic comma. What if the writer wants to join an independent and a dependent clause, but they want the dependent clause to come first? In a periodic sentence, the independent clause appears after its dependent clause. Writers use periodic sentences to create an element of surprise or suspense, as the main idea of the sentence occurs last--this is why these sentences are sometimes called suspended sentences. Thus, a suspended comma comes at the end of a dependent clause if it is immediately followed by an independent clause.* *These are sometimes called periodic commas; however, students can easily be confused by that name, as periods are also a type of punctuation. |
Two independent clauses can be connected in four different ways:
For every method but the first, there is a punctuation mark that clearly delineates where one clause ends before another clause starts. This is why a conjunction can combine two independent clauses only if there's a comma after the word right before the conjunction. Since this comma is used for a balanced sentence, it's called a balanced comma.
Can any conjunction join two independent clauses? No. Subordinating conjunctions subordinate, meaning they functionally give their clause less weight than other clauses (these start adverbial dependent clauses, which we'll look at in the next section). However, both of the other two types of conjunctions—coordinating conjunctions and conjunctive adverbs—can join independent clauses by using a balanced comma.
EXAMPLE, COORDINATING CONJUNCTION:
EXAMPLE, CONJUNCTIVE ADVERB:
NB: This convention only holds true when a coordinating conjunction is being used as a coordinating conjunction. For can sometimes function as a preposition (My dog Smuckers likes treats for a reward) and so can sometimes function as a subordinating conjunction (I held her hand so she wouldn't be lonely). Similarly, this convention only holds true when a conjunctive adverb is being used as a conjunction (My dog Smuckers likes treats, despite the fact that they give him gas) and not as an adverb modifying the second clause (My dog Smuckers likes treats, despite this I need to find a new kind of reward for him). In this second incorrect case, the two clauses should be joined by a semicolon with a circuit comma after the conjunctive adverb (My dog Smuckers likes treats; despite this, I need to find a new kind of reward for him).
- using a conjunction
- using a colon (but only if clause 1 introduces clause 2)
- using a semicolon (but only if clause 2 starts with a conjunctive adverb or mirrors clause 1's syntax)
- using a dash (but only if clause 2 is only tangentally related to clause 1)
For every method but the first, there is a punctuation mark that clearly delineates where one clause ends before another clause starts. This is why a conjunction can combine two independent clauses only if there's a comma after the word right before the conjunction. Since this comma is used for a balanced sentence, it's called a balanced comma.
Can any conjunction join two independent clauses? No. Subordinating conjunctions subordinate, meaning they functionally give their clause less weight than other clauses (these start adverbial dependent clauses, which we'll look at in the next section). However, both of the other two types of conjunctions—coordinating conjunctions and conjunctive adverbs—can join independent clauses by using a balanced comma.
EXAMPLE, COORDINATING CONJUNCTION:
EXAMPLE, CONJUNCTIVE ADVERB:
NB: This convention only holds true when a coordinating conjunction is being used as a coordinating conjunction. For can sometimes function as a preposition (My dog Smuckers likes treats for a reward) and so can sometimes function as a subordinating conjunction (I held her hand so she wouldn't be lonely). Similarly, this convention only holds true when a conjunctive adverb is being used as a conjunction (My dog Smuckers likes treats, despite the fact that they give him gas) and not as an adverb modifying the second clause (My dog Smuckers likes treats, despite this I need to find a new kind of reward for him). In this second incorrect case, the two clauses should be joined by a semicolon with a circuit comma after the conjunctive adverb (My dog Smuckers likes treats; despite this, I need to find a new kind of reward for him).
LOOSE COMMAS: Surrounding the Supplements
Appositives are nouns that immediately follow and rename another noun. A common error is putting commas around a single appositive: My dog, Smuckers, likes to play fetch. This is unneeded, as the appositive needs no separation from the word it renames, which is why My dog Smuckers likes to play fetch is correct.
However, there are such things as appositive commas. Appositive commas are used for appositive phrases, which occur when an appositive has modifiers other than an article; since an appositive is grammatically equal to the word it renames in all aspects, the commas are needed to isolate the modifiers to just one subject. For example, no commas are needed for My brother the clown likes to scare children. However, appositive commas are used for My brother, the overweight redheaded circus clown, likes to scare children.
However, there are such things as appositive commas. Appositive commas are used for appositive phrases, which occur when an appositive has modifiers other than an article; since an appositive is grammatically equal to the word it renames in all aspects, the commas are needed to isolate the modifiers to just one subject. For example, no commas are needed for My brother the clown likes to scare children. However, appositive commas are used for My brother, the overweight redheaded circus clown, likes to scare children.
Appositives are nouns that immediately follow and rename another noun. A common error is putting commas around a single appositive: My dog, Smuckers, likes to play fetch. This is unneeded, as the appositive needs no separation from the word it renames, which is why My dog Smuckers likes to play fetch is correct.
However, there are such things as appositive commas. Appositive commas are used for appositive phrases, which occur when an appositive has modifiers other than an article; since an appositive is grammatically equal to the word it renames in all aspects, the commas are needed to isolate the modifiers to just one subject. For example, no commas are needed for My brother the clown likes to scare children. However, appositive commas are used for My brother, the overweight redheaded circus clown, likes to scare children.
However, there are such things as appositive commas. Appositive commas are used for appositive phrases, which occur when an appositive has modifiers other than an article; since an appositive is grammatically equal to the word it renames in all aspects, the commas are needed to isolate the modifiers to just one subject. For example, no commas are needed for My brother the clown likes to scare children. However, appositive commas are used for My brother, the overweight redheaded circus clown, likes to scare children.
Nominal commas separate names from important titles that are usually linked with a name like Dr. John Frink, PhD or Mary DePalma, Esquire. While the same was once true for legacy names like Kurt Vonnegut Jr. or Thurston Howell III, commas are no longer used.
ATTRIBUTIVE COMMAS: Qualifing the Quotes
Attributive commas separate the author's or narrator's voice from the voices of others that are speaking of dialogue or giving a direct quote. Quotation marks alone are not enough, as "some" quotation marks do not demonstrate "dialogue" per se but are for emphasis. If the author's voice is before the quotation, the comma goes after the author's words: On page 13, Stevens claims, "No other scientist has found causality in this case." If the quotation comes before the author's words, the comma goes after the quotation but within the quotation marks: "I can't believe Monica word that," Jill said with a sneer.
Note that if the quotation is truncated to be part of a restrictive relative clause, the comma is ignored: Before the murder, Norman tells Marion that she "eats like a bird." For more on punctuating quotes, click the link.
Note that if the quotation is truncated to be part of a restrictive relative clause, the comma is ignored: Before the murder, Norman tells Marion that she "eats like a bird." For more on punctuating quotes, click the link.
VOCATIVE COMMAS: Isolating the Interrogatives
Vocative commas separate interjections and nouns of direct address from the rest of the sentence. Remember that these words have no direct syntactic connection to the sentence subject, verbs, or complements: the vocative comma is placed to demonstrate that the interjection or noun of direct address is not connected. The comma occurs whether the word is at the start of the sentence (Hey, did you get the pie?) or at the end of the sentence (I can't believe you forgot the pie, bro!).
While adjectives must precede the word they modify (except in the case of predicate adjectives), adverbs can appear almost anywhere in a sentence. If an adverb is not either immediately before or after the word they modify, they need a emphatic comma. Here's an example: Alarmingly, Mike found the bloody knife in his trunk. Alarmingly modifies found, but since it is not beside it, the word gets a comma. This can also happen at the end of the sentence (Mike was charged with Vanessa's murder, unfortunately) as well as in the middle of the sentence (Mike realized that his arrest, surprisingly, was on his birthday).
Adverbs are not always just single words: prepositional phrases are also adverbial or adjectival by nature. These phrases are supposed to follow the words they modify, as in the sentence We'll play Madden after eating some ice cream; no comma is needed in the sentence since the prepositional phrase follows the word it modifies (play). However, emphatic commas are needed if the phrase is moved before the word it modifies: After eating some ice cream, we'll play Madden. Note that this is also true for participle and infinitive phrases.
Adverbs are not always just single words: prepositional phrases are also adverbial or adjectival by nature. These phrases are supposed to follow the words they modify, as in the sentence We'll play Madden after eating some ice cream; no comma is needed in the sentence since the prepositional phrase follows the word it modifies (play). However, emphatic commas are needed if the phrase is moved before the word it modifies: After eating some ice cream, we'll play Madden. Note that this is also true for participle and infinitive phrases.
Conjunctive adverbs are always separated from the rest of the sentence by commas when at the start of a sentences (Moreover, these trends can be seen in the native populations) or in the middle of a sentence (When surveying the population, however, the results were surprising). However, be mindful that conjunctive adverbs modify the entire sentence to create a smooth transition (Additionally, the results from the latest survey show an overall sharp downturn in support); if the word only describes a single word, it is just a regular adverb and may not need a comma (The results from the latest survey additionally show an overall sharp downturn in support). This is also why i.e. (id est, Latin for that is) and e.g. (exempli gratia, Latin for for example) are followed by commas, as they are both conjunctive adverbs. Click the link for more information on conjunctive adverbs.
INTEROGATIVE COMMAS: Adding on an Ask
RESOLUTION COMMAS: Clarifying the Convoluted
REVERSING COMMAS: When You Wanna Be Upfront
Clausal commas separate clauses. While all clauses used to be separated by commas, modern usage only separates clauses with a comma for periodic sentences (where a dependent clause is followed by an independent clause) and balanced sentences (where there are multiple independent clauses).
Loose commas (also called periodic commas) exist in periodic sentences and follow the dependent clause. In the sentence Once I murder the countess, I will inherit the Carlyle Diamond, a comma must follow the word countess to show that the independent (and thus most important) clause is to follow.
Cumulative sentences (where dependent clauses follow independent clauses) don't need clausal commas. Neither do noun clauses or restrictive relative clauses (My boss that wears the ugly dresses founded the company). However, nonrestrictive relative clauses do need commas (My boss, who founded the company, wear the ugliest dresses to work). For more information on clauses, click the link below.
Loose commas (also called periodic commas) exist in periodic sentences and follow the dependent clause. In the sentence Once I murder the countess, I will inherit the Carlyle Diamond, a comma must follow the word countess to show that the independent (and thus most important) clause is to follow.
Cumulative sentences (where dependent clauses follow independent clauses) don't need clausal commas. Neither do noun clauses or restrictive relative clauses (My boss that wears the ugly dresses founded the company). However, nonrestrictive relative clauses do need commas (My boss, who founded the company, wear the ugliest dresses to work). For more information on clauses, click the link below.
UNIT COMMAS: When You Wanna Be Upfront
Comma separate every three digits in a number (3,468,972,601). When spelling out numbers fully, commas go in the same places: Three billion, four hundred sixty-eight million, nine hundred seventy-two thousand, six hundred and one. For more on numbers in writing, click the link.
Chronical commas divide units of time when they are out of order from smallest increment to largest increment. When listed as time day date month year, no commas are used-- 11:15 AM Thursday 14 September 2003; this is typically the way time is written in European countries. In the Americas, we write dates as day, month date, year, time and require commas-- Thursday, September 14, 2003, 11:15 AM. Chronical commas also divide units of elapsed time (e.g., four hours, thirteen minutes, and fifty-five seconds)
Geographical commas separate locations from the most specific location to the most general location. Typically the order is specific room, room or apartment number, building name, address, city, county, state, country, planet, galaxy: Mr. Coon's classroom, E100, Frederick High School, 5690 Tipple Pkwy, Frederick, Weld, Colorado, United States, Earth, Milky Way. Notice that zoning codes like ZIP codes are not part of this list, which is why there is no comma between a places and ZIP codes.
LISTING COMMAS: When You Wanna Be Upfront
Serial commas separate items in a list. A comma should follow every item in a list except the last one (I need to buy apples, bread, cinnamon, and pasta).
The serial comma before the coordinating conjunction is called the Oxford comma or Harvard comma and is not used by some style guides. MLA requires the Oxford comma as it leads to grater clarity. In the sentence My heroes are my parents, Batman and George Washington, the comma use implies that Batman and George Washington are the speaker's parents. Using the Oxford comma (My heroes are my parents, Batman, and George Washington) corrects this error.
Additionally, if the list items contain commas, they are instead separated by semicolons: I have dated Johnny, the quarterback of the football team; Norwood, the senior class president; and Ronnie, the only male cheerleader on the squad.
The serial comma before the coordinating conjunction is called the Oxford comma or Harvard comma and is not used by some style guides. MLA requires the Oxford comma as it leads to grater clarity. In the sentence My heroes are my parents, Batman and George Washington, the comma use implies that Batman and George Washington are the speaker's parents. Using the Oxford comma (My heroes are my parents, Batman, and George Washington) corrects this error.
Additionally, if the list items contain commas, they are instead separated by semicolons: I have dated Johnny, the quarterback of the football team; Norwood, the senior class president; and Ronnie, the only male cheerleader on the squad.
COORDINATING COMMAS: When You Wanna Be Upfront
Coordinate commas separate two adjectives that describe the same qualities of an object but do not separate different qualities.
How does this work? Adjectives that precede the noun are put in the following order in American English:
Here is an example, and notice that it has no commas: The plans called for an impressive sky-high modern rectangular grey German concrete sixty-story skyscraper. Yet if I changed the sentence to The plans called for a modern, state-of-the-art sixty-story skyscraper, I need a multimod comma between modern and state of the art, as both are age adjectives. The sentence I bought two thick, solid posts also needs a multimod comma, as solid and thick are both size adjectives. Click the link below for more details on modifiers and their commas.
How does this work? Adjectives that precede the noun are put in the following order in American English:
- determiner (articles, possessives, and demonstrative pronouns)
- numbers (quantities and ordinal numbers)
- observations and opinions (subjective or arguable qualities as well as temporary states)
- size (includes all proportions: height, width, depth, breadth, weight, density, thickness)
- age
- shape (including form)
- color
- origin
- material
- purpose
Here is an example, and notice that it has no commas: The plans called for an impressive sky-high modern rectangular grey German concrete sixty-story skyscraper. Yet if I changed the sentence to The plans called for a modern, state-of-the-art sixty-story skyscraper, I need a multimod comma between modern and state of the art, as both are age adjectives. The sentence I bought two thick, solid posts also needs a multimod comma, as solid and thick are both size adjectives. Click the link below for more details on modifiers and their commas.
ANTITHESIS COMMAS: When You Wanna Be Upfront
GAPPING COMMAS: When You Wanna Be Upfront
Twelve is an important number in Western thought. There are twelve months in a year, twelve hours of morning and twelve of night each day, twelve signs of the Babylonian zodiac, twelve cardinal gods in both Norse and Greco-Roman mythology, twelve tribes of Israel. Ancient civilizations believed twelve was a divine number because it is an abundant number, a highly composite number, a Pell number, and a sublime number. Several of those civilizations had base-12 counting systems, including the Sumerians, Egyptians, and early Romans.
The Western reverence for the number twelve is only matched by its revulsion for the number thirteen—one past perfect, a number with no factors and no corollaries in the natural world. This gave the presence of a thirteenth member the reputation of being unlucky or even wicked in literature. At a wedding hosted by the twelve cardinal Greek gods, an uninvited thirteenth goddess named Eris, Goddess of Discord, incited an argument that started the Trojan War. Of the thirteen people at the Last Supper, one of them—Judas Iscariot—betrayed his benefactor Jesus of Nazareth. There were originally twelve seats at the mythical round table for King Arthur and his knights, but then they added a thirteenth spot for Lancelot, the knight that had an affair with Arthur's wife Guinevere and caused a civil war.
What does any of this have to do with grammar? So far, we've looked at twelve different commas that all serve to separate different groups of words for different purposes. This means we can sum up a comma's job in two simple words: commas separate.
At least we could, if not for the thirteenth type of comma—the misfit, the spoiler, the betrayer of the inherent nature of commas. Let's end our exploration of commas with the most easily confused and misused one: the gapping comma.
The Western reverence for the number twelve is only matched by its revulsion for the number thirteen—one past perfect, a number with no factors and no corollaries in the natural world. This gave the presence of a thirteenth member the reputation of being unlucky or even wicked in literature. At a wedding hosted by the twelve cardinal Greek gods, an uninvited thirteenth goddess named Eris, Goddess of Discord, incited an argument that started the Trojan War. Of the thirteen people at the Last Supper, one of them—Judas Iscariot—betrayed his benefactor Jesus of Nazareth. There were originally twelve seats at the mythical round table for King Arthur and his knights, but then they added a thirteenth spot for Lancelot, the knight that had an affair with Arthur's wife Guinevere and caused a civil war.
What does any of this have to do with grammar? So far, we've looked at twelve different commas that all serve to separate different groups of words for different purposes. This means we can sum up a comma's job in two simple words: commas separate.
At least we could, if not for the thirteenth type of comma—the misfit, the spoiler, the betrayer of the inherent nature of commas. Let's end our exploration of commas with the most easily confused and misused one: the gapping comma.
Gapping commas replace elided words in parallel clauses and asyndetic modifiers
Told you it was confusing.
To put it simply, gapping commas are only used for solecism, which is a set of methods that violate traditional grammatical conventions for stylistic reasons. One of the types of solecism is elision, intentionally cutting out parts of a sentence that should logically be there. When a letter or group of letters gets elided (cut) out of a word, they are replaced with an apostrophe to show something is missing (e.g., can not becomes can't). This is called syncope.
However, when not just letters but an entire word or group of words are elided, they aren't replaced with an apostrophe but with a comma to close the gap between the remaining words. A gapping comma.
While every other comma separates, the gapping comma does the opposite: it connects the two remaining remnants of the sentence. Not just anything can be cut out of a sentence, however. Gapping commas can only be used for asyndeton and ellipsis.
Using a gapping comma is like cooking beef Wellington: when done correctly, it's really impressive, but it's very hard to pull off without making a mistake. The gapping comma is... just the worst, so avoid trying to use it until you feel really confident in your writing.
To put it simply, gapping commas are only used for solecism, which is a set of methods that violate traditional grammatical conventions for stylistic reasons. One of the types of solecism is elision, intentionally cutting out parts of a sentence that should logically be there. When a letter or group of letters gets elided (cut) out of a word, they are replaced with an apostrophe to show something is missing (e.g., can not becomes can't). This is called syncope.
However, when not just letters but an entire word or group of words are elided, they aren't replaced with an apostrophe but with a comma to close the gap between the remaining words. A gapping comma.
While every other comma separates, the gapping comma does the opposite: it connects the two remaining remnants of the sentence. Not just anything can be cut out of a sentence, however. Gapping commas can only be used for asyndeton and ellipsis.
- Asyndeton is the elision of needed conjunctions out of a sentence for emphasis. Julius Caesar's famous address to Rome declaring that "I came, I saw, I conquered" (instead of I came, I saw, and I conquered). More often, asyndeton is used to cut a conjunction that should combine two modifiers: "Silently, stealthily, Mandy crept down the dark stairs" (instead of silently and stealthily).
- Ellipsis is the elision of a verb and other words in a second parallel clause of a balanced sentence that are repeated from the first clause. Here's an example: His pressed shirt was white, and his tie, bright orange (the comma replaces the second was). Here's another with more words elided: The northern flank of the Confederate Army was led by General Robert E. Lee; the southern, by Stonewall Jackson. This can only happen if the first and second clauses are structurally alike with the same verb, and enough words must be left over to make logical sense (like the word by in the last example, since the object of a preposition can't lose its preposition). If this wasn't complicated enough, solecistic ellipsis is not the same as rhetorical ellipsis, where a section of a direct quote is replaced by an ellipsis mark ( . . . ). The elided clause in this case is also not an elliptical clause, which is a clause that leaves words out that are intuitive and doesn't use any punctuation to signify elision (e.g., When ignited, the candle flame burns green [should be when it is ignited]; Nate runs faster than I can [should be than I can run]).
Using a gapping comma is like cooking beef Wellington: when done correctly, it's really impressive, but it's very hard to pull off without making a mistake. The gapping comma is... just the worst, so avoid trying to use it until you feel really confident in your writing.
This article was last updated on 19 February 2026.
In Old English, comma use was surprisingly easy, as commas were the only punctuation mark that showed separation. Commas came between every clause no matter what, they offset subtitles and all list items, and they delineated unneeded information. Yet as syntax and English became more complex, we developed more nuanced punctuation marks. Take the following sentence, where the only punctuation mark that separates is a comma: At 4,55 in the recording, the senator clearly refers to his campaign stops in Des Moines, Iowa, Memphis, Tennessee, and Grand Rapids, Michigan, a comment that Dr. Morgan says in his book, "proves that the candidate is lying, as he did not set foot in those cities until the following month," 34.
That sentence, with its eleven commas, demonstrates why other punctuation marks developed. Colons were developed to show that two things were separate and related at the same time, like the minutes and second of time (4:55). Semicolons were developed to help separate items in a list where those items themselves had commas-- by writing the list Des Moines, Iowa; Memphis, Tennessee; and Grand Rapids, Michigan, the writer clarifies that the senator is speaking of three places, not six. Parentheticals and dashes were developed to show whether the separated information is essential (dash) or nonessential (parenthesis and brackets). With modern punctuation, the sentence terms are clearer: At 4:55 in the recording, the senator clearly refers to his campaign stops in Des Moines, Iowa; Memphis, Tennessee; and Grand Rapids, Michigan--a comment that Dr. Morgan says in his book, "proves that the candidate is lying, as he did not set foot in those cities until the following month" (34).
Of course, while these other punctuation marks are specialized to do very specific tasks, commas are relegated to taking care of every other kind of separation, leading to the common confusion of exactly what commas do and when they are needed. The following are the thirteen types of commas and what they do in a sentence.
There are three classes of commas. Clausal commas are used to show separations between clauses. Ordinal commas are used to separate items in a sequence for the sake of clarity. Transformative commas, for the most part, are used to distinguish items that modify the entire sentence from the sentence itself, though one transformative comma breaks all the rules of commas and doesn't separate but combines. In total, there are thirteen distinct kinds of commas—fitting, given how so many students rely on luck and guesswork to place commas.
That sentence, with its eleven commas, demonstrates why other punctuation marks developed. Colons were developed to show that two things were separate and related at the same time, like the minutes and second of time (4:55). Semicolons were developed to help separate items in a list where those items themselves had commas-- by writing the list Des Moines, Iowa; Memphis, Tennessee; and Grand Rapids, Michigan, the writer clarifies that the senator is speaking of three places, not six. Parentheticals and dashes were developed to show whether the separated information is essential (dash) or nonessential (parenthesis and brackets). With modern punctuation, the sentence terms are clearer: At 4:55 in the recording, the senator clearly refers to his campaign stops in Des Moines, Iowa; Memphis, Tennessee; and Grand Rapids, Michigan--a comment that Dr. Morgan says in his book, "proves that the candidate is lying, as he did not set foot in those cities until the following month" (34).
Of course, while these other punctuation marks are specialized to do very specific tasks, commas are relegated to taking care of every other kind of separation, leading to the common confusion of exactly what commas do and when they are needed. The following are the thirteen types of commas and what they do in a sentence.
There are three classes of commas. Clausal commas are used to show separations between clauses. Ordinal commas are used to separate items in a sequence for the sake of clarity. Transformative commas, for the most part, are used to distinguish items that modify the entire sentence from the sentence itself, though one transformative comma breaks all the rules of commas and doesn't separate but combines. In total, there are thirteen distinct kinds of commas—fitting, given how so many students rely on luck and guesswork to place commas.