Does a prequel come first?

Excuse me, I'm a bit confused about something. I was reading about movie sequels and prequels, and I came across this question: "Does a prequel come first?" Now, I'm wondering, isn't the whole idea of a prequel that it's set before the events of the original movie or series? So, by definition, wouldn't it logically have to come first in the timeline of the story? Or am I misunderstanding something here? Could you please clarify this for me? Thanks in advance.