Here's a breakdown:
* Independent clause: A group of words that can stand alone as a complete sentence. It has a subject and a verb.
Example:
* "The sun is shining, but it's cold outside."
In this example, "The sun is shining" and "it's cold outside" are both independent clauses. They are connected by the coordinating conjunction "but," so a comma is required.
Here are some additional points to remember:
* Don't use a comma if the two clauses are not independent:
* "I love my dog, but he barks a lot." (The second part is not a complete sentence.)
* If the conjunction is "and," "or," "nor," "for," or "yet," you generally don't need a comma.
Remember, the comma before "but" serves to separate two complete thoughts, providing a smooth transition between them.