A prologue is a piece of writing found at the beginning of a literary work, before the first chapter and separate from the main story.

Is prologue before or after the story?

A prologue is a scene that comes before the story. It's something of import but something that doesn't flow with the chronology of the story.

Does the prologue come before chapter 1?

Generally, the prologue is the first anything in the book. That is, it's the first section the reader reads. If you're asking if it goes before or after the labeling of Part One, it depends on what the prologue is saying.