Commas: “For the Innocent, the Eager, and the Doomed”

“If you bend a branch until it’s horizontal, the sap will slow to a stopping point: a comma or colon, made of leaves grown into one another and over one another and hardened. Out of this pause comes a flower, which unfolds itself in spirals, as if the leaf form, unable to keep to its line, had begun to pivot.”

Alice Oswald

As I was proofreading my book, I had this growing sense that I was not satisfied with my competence of comma usage, so I gathered some sources and compiled a list of occasions when commas are called for (and sometimes when they are not). I read Elizabeth Gordon’s The New Well-Tempered Sentence and June Casagrande’s The Best Punctuation Book, Period to research the content of this post. This list, unfortunately, is not exhaustive, but it is extensive.

1. Independent Clauses
   • Short Independent Clauses: Short independent clauses joined by and can be used without a comma.
   • Short, Successive Independent Clauses: Commas may be used between short, successive independent clauses that are equal in value. These clauses should not have commas within them.
   • Coordinating & Correlative Conjunctions: Use a comma between two independent clauses joined by a coordinating or correlative conjunction. Place the comma before the conjunction. For correlative conjunctions, the comma is positioned before the second correlative conjunction.
   • So That: Do not use a comma before the subordinating conjunction so that. Sometimes this subordinating conjunction is rendered as so while omitting that, which is then only implied.
   • Semicolon: Use a semicolon between two independent clauses if you want to combine them into a single sentence without a comma and a conjunction.
   • Conjunctive Adverb: When two independent clauses are joined by a conjunctive adverb, a semicolon precedes the conjunctive adverb, and a comma follows it.

2. Relative Dependent Clauses
   • Restrictive: Do not use commas to set off restrictive relative clauses.
     • A restrictive clause is essential to the meaning of the clause that it modifies.
   • Nonrestrictive: Use commas to set off nonrestrictive relative clauses.
     • A nonrestrictive clause is nonessential or parenthetical to the meaning of the clause that it modifies.

3. Adverbial Dependent Clauses
   • Introductory: An adverbial dependent clause that precedes the main clause is usually set off by a comma whether it is restrictive or nonrestrictive.
   • Short Introductory: If a short adverbial dependent clause precedes a main clause and the sentence is clear, the comma may be omitted.
   • Middle of the Sentence: Commas are placed before and after adverbial phrases or adverbial dependent clauses that occur in the middle of a sentence between the subject and the verb.
   • Contrast: In cases of extreme contrast, use a comma before an adverbial dependent clause that follows its main clause.
   • Restrictive: A restrictive adverbial dependent clause that follows a main clause should not be set off by a comma.
   • Nonrestrictive: A nonrestrictive adverbial dependent clause that follows a main clause is preceded by a comma.

4. Adverbial Phrases
   • Introductory: Adverbial phrases at the beginning of sentences are often followed by a comma.
   • Short Introductory Adverbial Phrases: A comma is sometimes omitted after a short introductory adverbial phrase. (Short phrases are less than four words.)
     • A comma is not used after an introductory adverbial phrase immediately preceding the verb it modifies.
   • Middle of the Sentence: Commas are placed before and after adverbial phrases or adverbial dependent clauses that occur in the middle of a sentence between the subject and the verb.
   • Pre- or Post-verb Modification: Adverbs or adverbial phrases (e.g., adverbial prepositional phrases) inserted before or after the structure they modify may or may not be set off with commas.

5. Participial & Infinitival Phrases
   • Introductory participial and infinitival phrases are set off by a comma, except when they immediately precede a verb or subject that they are a part of.

6. Appositives
   • If an appositive is restrictive, do not set it off with commas. If it is restrictive, omit the commas.
   • Proper Names: Omit commas in an appositive that is a proper name.

7. Parenthetical Clauses, Phrases, Words
   • Use a comma to separate a parenthetical (i.e. nonrestrictive or nonessential) element from the rest of a sentence.
     • For parenthetical elements that are less logically related to the rest of the sentence, use em dashes or parentheses.

8. Complementary & Antithetical Phrases
   • Use commas to separate complementary or antithetical phrases. And set off those phrases from the rest of the sentence with commas.
     • E.g.: Your conclusions lead me away from, rather than toward, what you want me to think.
   • Antithetical: Use commas to separate antithetical phrases and clauses beginning with not if those clauses and phrases are unessential to the sentence.
     • Short Antithetical Phrases: Do not use a comma to separate short antithetical phrases. E.g.: The sooner the better.
   • Interdependent Antithetical Clauses: Separate these with commas.
     • E.g.: The lower she sank, the better she felt.

9. Absolute Phrases
   • Use commas separate absolute phrases from the rest of the sentence.

10. Adjectives
    • Coordinate Adjectives are separated by a comma. Adjectives are coordinated if they modify the same element and their positions can be reversed without altering the meaning (i.e., they are of equal rank). In this case, a comma is a substitute for and.
    • Cumulative Adjectives are not separated by a comma because they build upon each other, and their order cannot be reversed.
    • Post-noun Modification: Adjectives inserted directly after the nouns they modify may or may not be set off with commas.

11. Quotations, Proverbs, Maxims
    • Use commas to set off quotations, proverbs, maxims, or similar expressions either at the beginning, middle, or end of sentences.
    • Subject, Predicate Nominative, Restrictive Appositive: If a quotation, proverb, or maxim is the subject, predicate nominative, or restrictive appositive, do not use commas.
    • Flow: If a quotation flows into or integrates well with the sentence, do not use commas to set it off.

12. Quotation Marks, Parentheses, Brackets
    • Use commas to separate a quotation from other parts of a sentence.
      • When a quotation is preceded by an attribution (e.g., he said), the comma is placed immediately before the quotation marks.
      • When a quotation is followed by an attribution, a comma is placed inside the closing quotation mark.
      • When a quotation is followed by an attribution that ends in a question or exclamation mark, do not use a comma after the question or exclamation mark.
      • A comma goes inside the quotation marks but outside the parentheses or brackets in quoted material.
    • Colons: Use a colon before a quotation to add emphasis.

13. Items in a Series
    • Use a comma to separate three or more items in a series: words, phrases, or clauses.
      • Try to make each item parallel in structure.
      • Do not use commas between items that are considered a whole.
      • If each item in a series is joined by a conjunction, do not use a comma.
      • The last item in a series of words, phrases, or clauses is often preceded by the coordinating conjunction and. Use a comma before and.
      • When the last or second-to-last item in a series contains its own conjunction, use the Oxford comma.
      • Do not use a comma before an ampersand.
      • When items within a series contain their own commas, use a semicolon to separate each item in the series.
      • When each item in a series is long, you may use semicolons instead to separate the items.

14. Confirmatory Question
    • Use a comma before a confirmatory question that occurs in a declarative sentence.

15. Direct Address
    • Use a comma to set off nouns of direct address.

16. Bits
    • O: Do not use a comma to set off the vocative O.
    • Oh: Use a comma to set off the exclamatory oh.
    • Interjections, Transitional/Sentence Adverbs: Use commas to set off interjections, transitional/sentence adverbs.
    • Continuity: Expressions like in fact, perhaps, and therefore are sometimes set off by commas, but if expressions do not break the flow or a pause is not needed, the commas can be omitted.
    • That is, e.g., i.e., etc., specifically, namely, respectively: Use a comma to set off these phrases when they introduce a series or an example.
    • Including, such as: Using a comma before these terms is optional, but do not use it after them.

17. Mistaken Junctions
    • Use a comma between elements to prevent ambiguity.
      • E.g.: “Shortly after, the convocation commenced its pompous tones and hollow notes.”

18. Similar Words
    • Use commas to separate words that are similar in spelling or sound.
      • E.g.: “Whatever happens, happens because it must.”

19. Omitted Words
    • Use a comma to indicate words that have been omitted from a context in which the omitted words are readily understood.
      • E.g.: The farmer takes a wife; the wife, a child; the child, a dog; the dog, another child; the other child, another dog; the other dog, a pet rabbit to chase.

20. Unrelated Numbers
    • Use a comma to separate numbers that are unrelated to avoid ambiguity.
      • E.g.: In 1905, 763 mustaches were shaved off in a county in Massachusetts alone.

21. Place of Residence or Origin
    • When a phrase indicating a person’s residence or origin is used beside a person’s name, you may omit the comma, especially with historical figures whose origin is regularly stated with their name.

22. Person’s Name, Title, or Position
    • Words and phrases that identify a person’s title or position are separated from the person’s name by commas; this may be viewed as an appositive.
    • Family Names: Avoid using commas before roman numerals in family names; Jr. and Sr. may go with or without commas around them.

23. Addresses
    • Use commas to separate parts of addresses and names of geographical places.

24. Dates
    • Using a comma between a month and year in a date is optional, but use commas to separate the year when it is followed by the day of the month.

25. Letters
    • Use a comma after a salutation in an informal letter.
    • Use a comma after a complimentary close in a letter.
    • Greetings: Dear in Dear Jane, is an adjective and is part of the direct address, unlike Hey, John.

26. Digits
    • With numerical values over 999, use a comma after every third digit.

27. Inverted Names & Phrases
    • Use commas to separate inverted names and phrases, such as in a bibliography or index.