1. "Or" as a Coordinating Conjunction:
* When "or" connects two independent clauses: You *do* need a comma before "or."
* Example: "I could go to the park, or I could stay home and read."
* When "or" connects two phrases or words: You *don't* need a comma before "or."
* Example: "Would you like tea or coffee?"
2. "Or" in Lists:
* When "or" is used in a list, the comma placement depends on the structure of the list:
* If there are three or more items in the list: Use a comma before "or."
* Example: "I need milk, bread, or eggs."
* If there are only two items in the list: The comma is optional.
* Example: "I need milk or bread." (Comma is optional)
3. "Or" in Parentheticals:
* When "or" is used within a parenthetical phrase, you may or may not need a comma depending on the phrase's length and structure.
* Example: "The dog, a Labrador or a Golden Retriever, was very friendly." (Comma is optional)
In general, think of it like this:
* If the clauses, phrases, or words connected by "or" could stand alone as sentences, use a comma.
* If they couldn't, you probably don't need a comma.
Remember, it's always best to err on the side of caution and use a comma if you're unsure. However, the most important thing is to create clear and understandable writing!