1. Joining Independent Clauses:
* With coordinating conjunctions (FANBOYS): Use a comma before coordinating conjunctions (for, and, nor, but, or, yet, so) that join two independent clauses.
* Example: The sun was setting, and the birds were singing.
2. Introducing Lists:
* Before a series of items: Use a comma to separate items in a list of three or more.
* Example: We bought apples, bananas, and oranges.
* After an introductory phrase: Use a comma after an introductory phrase or dependent clause that comes before the main clause.
* Example: After the long drive, we were exhausted.
3. Setting Off Nonessential Phrases or Clauses:
* Appositives: Use commas to set off appositives (words or phrases that rename or explain a noun).
* Example: My dog, a golden retriever, loves to play fetch.
* Parentheticals: Use commas to set off parentheticals (words or phrases that add extra information but are not essential to the sentence).
* Example: The book, as I mentioned earlier, is very popular.
* Restrictive vs. Nonrestrictive Clauses: Use commas to set off nonrestrictive clauses (clauses that add extra information but don't define the noun). Do not use commas with restrictive clauses (clauses that are essential to the meaning of the sentence).
* Example: The house, which is painted blue, is on the corner. (nonrestrictive)
* Example: The house that is painted blue is on the corner. (restrictive)
4. Dates, Addresses, and Titles:
* Dates: Use commas to separate the day of the month from the year.
* Example: July 4, 1776
* Addresses: Use commas to separate the city from the state and the state from the zip code.
* Example: 123 Main Street, Anytown, CA 12345
* Titles: Use commas to set off titles that follow a person's name.
* Example: John Smith, PhD
5. Other Common Uses:
* Direct Address: Use a comma to set off a direct address (a person's name).
* Example: John, can you please pass the salt?
* Interjections: Use a comma to set off interjections (words or phrases that express strong emotions).
* Example: Wow, that's amazing!
* Misplaced Modifiers: Use a comma to separate a misplaced modifier from the word it modifies.
* Example: I saw a bear, running through the woods.
Remember: These are just some of the most common comma rules. There are always exceptions and more nuanced situations. It's a good idea to consult a grammar guide or style manual if you are unsure about a particular comma use.