* Before "mais": A comma is required before "mais" when it connects two independent clauses. Think of it like "but" in English.
* Example: J'aime le chocolat, mais je n'aime pas le café. (I like chocolate, but I don't like coffee.)
* After "mais": A comma is not required after "mais".
* Example: J'ai essayé de l'appeler, mais il n'a pas répondu. (I tried to call him, but he didn't answer.)
In summary: Commas are used with "mais" in the same way they are used with "but" in English.