If the clauses make sense on their own, you don’t need to use a comma. For example: Albert was excited about eating. He wanted to use a knife and fork.

That's if you're using the Oxford comma, in any case. The Oxford comma is 100 percent optional, although advocates say it’s necessary for removing ambiguity in sentences. The Oxford comma rule ...

A run‐on sentence is two or more independent clauses joined together with insufficient punctuation. This means that there are two or more complete sentences fused into one sentence. Use a colon: a ...