1. Independent Clauses:
* Connecting with Conjunctions: Use a comma before coordinating conjunctions (for, and, nor, but, or, yet, so) when joining two independent clauses.
* Example: "The sun was setting, and the birds were singing."
* Semicolon as an Alternative: You can also use a semicolon instead of a comma and conjunction.
* Example: "The sun was setting; the birds were singing."
2. Introductory Phrases and Clauses:
* Phrases: Use a comma after introductory phrases (prepositional, participial, infinitive, etc.).
* Example: "After a long day, I was ready for bed."
* Clauses: Use a comma after introductory dependent clauses (subordinate clauses).
* Example: "Because it was raining, we stayed inside."
3. Nonessential Phrases and Clauses:
* Phrases: Use commas to set off nonessential phrases (phrases that can be removed without changing the sentence's core meaning).
* Example: "The car, which was red, was parked in the driveway."
* Clauses: Use commas to set off nonessential clauses (clauses that can be removed without changing the sentence's core meaning).
* Example: "My friend, who lives in New York, is coming to visit."
4. Items in a Series:
* Use commas to separate items in a list of three or more.
* Example: "I bought apples, oranges, and bananas."
* Comma Before "and" (Optional): The Oxford comma (comma before the "and" in a series) is a matter of style.
5. Dates, Addresses, and Names:
* Dates: Use a comma between the day and year.
* Example: "July 4, 1776."
* Addresses: Use a comma between the city and state, and between the state and zip code.
* Example: "Chicago, Illinois 60601."
* Names: Use a comma after the name of a person being addressed.
* Example: "Please, John, let me know what you think."
6. Other Uses:
* Interjections: Use commas to set off interjections.
* Example: "Oh, that's great news!"
* Direct Address: Use commas to set off direct address.
* Example: "John, can you pass the salt?"
* After a Question Mark or Exclamation Point: Use a comma after a question mark or exclamation point if the sentence continues.
* Example: "Is that your car? Yes, it is."
Remember: These rules are a guide, and there are exceptions. Context and clarity are key. Always consult a style guide or dictionary for more specific information.