1. Independent Clauses:
* Joining two complete sentences: Use a comma *before* the conjunction (and, but, for, nor, yet, so) that joins them.
* Example: "The sun was shining, and the birds were singing."
2. Introductory Phrases and Clauses:
* Before a dependent clause: Use a comma after an introductory phrase or clause that comes before the main clause.
* Example: "After a long day, I was ready for bed."
3. Lists and Series:
* Between items in a list: Use a comma after each item in a list of three or more items.
* Example: "I need milk, eggs, bread, and cheese from the store."
* Before the conjunction: Use a comma before the conjunction ("and" or "or") that joins the last two items in a list.
* Example: "We went to the park, the zoo, and the museum."
4. Nonessential Phrases and Clauses:
* Set off phrases or clauses that add extra information: Use commas to separate these elements from the main clause. They're not essential to the sentence's meaning.
* Example: "My friend, who lives in London, is visiting this week."
5. Direct Address:
* When addressing someone directly: Use a comma after the person's name.
* Example: "John, can you please pass the salt?"
6. Dates and Locations:
* Dates: Use a comma between the day of the month and the year.
* Example: "My birthday is on September 15, 2023."
* Locations: Use a comma between the city and state.
* Example: "She lives in Seattle, Washington."
7. Interjections and Appositives:
* Interjections: Use a comma after an interjection (words like "oh," "well," "wow," "however").
* Example: "Oh, I didn't realize that."
* Appositives: Use commas to set off appositives (words or phrases that rename or explain a noun).
* Example: "My sister, Emily, is a doctor."
Important Notes:
* Don't overuse commas! Use them sparingly and only when necessary.
* Context matters: Some rules have exceptions based on the context of the sentence.
* Use a comma checker: Online tools can help you identify comma errors.
For further clarification and examples, consider referring to a grammar handbook or website.