Why do you need a comma before the word but?

You don't always need a comma before the word "but." It depends on the structure of your sentence and whether "but" is connecting two independent clauses. Here's a breakdown:

When you DO need a comma before "but":

* Connecting two independent clauses: An independent clause can stand alone as a complete sentence. If you use "but" to connect two of these, you need a comma.

* Example: "I went to the store, but they were out of milk." (Both "I went to the store" and "they were out of milk" can be complete sentences on their own.)

When you DON'T need a comma before "but":

* Connecting two phrases or a dependent and independent clause: If "but" is connecting parts of a sentence that aren't both complete sentences, you don't need a comma.

* Example: "I bought a loaf of bread but forgot the cheese." ("Bought a loaf of bread" is a phrase, not a full sentence.)

In summary:

* Comma before "but": Use it when connecting two independent clauses.

* No comma before "but": Use it when connecting phrases, or a dependent and independent clause.

Let me know if you'd like more examples!