Should you use a comma before or? The answer depends on how you are using or. Always place a comma before or when it begins an independent clause, but if it begins a dependent clause, don’t. In a series (or list) of three or more items, you can use a comma before or, but this is a preference, not a rule.
People often get muddled about whether to place a comma before conjunctions like and, so, because, and or.