The comma is a small mark, but it is perhaps the most important punctuation in grammar. Despite that, comma confusion is one of the most common grammatical problems that students face. This blog attempts to help students with proper comma usage.
Short Summary (TL;DR)
1. The Pause
Commas, commas, commas. They often are a source of confusion. How do you use without getting lost in grammatical jargon? Thanks to Patricia T. O’Conner's book on grammar, Woe is I: The Grammarphobe’s Guide to Better English in Plain English, commas can easily be understood. We let her tell you about them in her own words:
"When you talk, your voice, with its pauses, stresses, rises and falls, shows how you intend your words to fit together. When you write, punctuation marks are the road signs (stop, go, yield, slow, detour) that guide the reader, and you wouldn’t be understood without them.
"If you don’t believe me, try making sense out of this pile of words:
Who do you think I saw the other day the Dalai Lama said my Aunt Minnie.
"There are at least two possibilities:
"Who do you think I saw the other day?" the Dalai Lama said. "My Aunt Minnie."
"Who do you think I saw the other day? The Dalai Lama!" said my Aunt Minnie."
"Punctuation isn’t some subtle, old-fashioned concept that’s hard to manage and probably won’t make much of a difference one way or another. It’s not subtle, it’s not difficult and it can make all the difference in the world.
2. Separate the Parts of Speech
If you get commas right, you will get most of your punctuation right. How do we use them?
Long and short division
Use a comma to separate big chunks (clauses) of a sentence with and between them.
If there’s no 'and' in between, use a semi-colon instead:
Use commas to separate a series of things or actions.
In a series, you can leave out the comma before "and". It’s just a matter of taste. 'And' can also be thought of as a separator, a break, so a comma often is unnecessary.
3. Comma with Subjects and their Verbs
With few exceptions, a comma should not separate a subject from its verb.
Incorrect: My friend Amanda, is a wonderful dancer.
Writers are often tempted to insert a comma between a subject and verb this way because speakers sometimes pause at that point in a sentence. But in writing, the comma only makes the sentence seem stilted.
Correct: My friend Amanda is a wonderful singer.
Be especially careful with long or complex subjects:
Incorrect: The things that cause me joy, may also cause me pain.
Correct: The things that cause me joy may also cause me pain.
Incorrect: Navigating through snow, sleet, wind, and darkness, is a miserable way to travel.
Correct: Navigating through snow, sleet, wind, and darkness is a miserable way to travel.
4. Comma After Introductions
Introductory clauses are dependent clauses that provide background information or "set the stage" for the main part of the sentence, the independent clause. For example:
Introductory phrases also set the stage for the main action of the sentence, but they are not complete clauses. Phrases don't have both a subject and a verb that are separate from the subject and verb in the main clause of the sentence. Common introductory phrases include prepositional phrases, appositive phrases, participial phrases, infinitive phrases, and absolute phrases.
Introductory words (SHFM)
Introductory words like however, still, furthermore, and meanwhile create continuity from one sentence to the next.
Comma Usage with Clauses
Commas are used to separate clauses in a complex sentence. The following examples show the use of commas in two complex sentences:
If the commas were removed, these sentences wouldn’t be as clear but the meaning would still be the same. There are different types of subordinate clause, though, and in some types the use of commas can be very important.
5. Commas with FANBOYs
Use commas to separate independent clauses when they are joined by any of these seven coordinating conjunctions: and, but, for, or, nor, so, yet.
6. Restrictive Clauses
A modifying clause can be either restrictive or nonrestrictive.
A restrictive modifying clause (or essential clause) is an adjective clause that is essential to the meaning of a sentence because it limits the thing it refers to. The meaning of the sentence would change if the clause were deleted. Because restrictive clauses are essential, they are not set off by commas.
7. Nonrestrictive Clauses
A nonrestrictive modifying clause (or nonessential clause) is an adjective clause that adds extra or nonessential information to a sentence. The meaning of the sentence would not change if the clause were to be omitted. Nonrestrictive modifying clauses are usually set off by commas.
8. "That" Clauses
Do not use commas to set off essential elements of the sentence, such as clauses beginning with that (relative clauses). That clauses after nouns are always essential. That clauses following a verb expressing mental action are also always essential.
That clauses after nouns:
That clauses following a verb expressing mental action:
9. Keep the 'Essential' and Cut Out the 'Nonessential'
Examples of other essential elements (no commas):
Examples of nonessential elements (set off by commas):
10. Geography, Dates, Addresses & Titles
Use commas to set off all geographical names, items in dates (except the month and day), addresses (except the street number and name), and titles in names.
11. Commas with Series & Lists
Use commas to separate three or more words, phrases, or clauses written in a series.
12. Shift Between Main Discourse and Quotation
Use a comma to shift between the main discourse and a quotation.
13. Comma Usage with Contrasts
Use a comma near the end of a sentence to separate contrasted coordinate elements or to indicate a distinct pause or shift.
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