Paste: Prologues

Prologues are extremely common. They are an additional chapter before Chapter One. Some people use them for prophetic reasons, e.g. writing a scene that comes at the end. Or, use it to talk from the main character's point of view in order to express how they "would never have known what was going to happen" and "how could they have known that the seemingly ordinary day would change their life forever". 
Personally, I think it is boring and pointless. Any hooks in the reader gained are cheating, you're not creating tension through cleverly built discrepancies and originality. No. Any hooks are built from the writer saying "you don't know this. And you won't know until you read on."  Technically, it's hostage-taking.
The other type of prologue is one that denotes a time shift in the past. So you might show your main character as a child, in order to prove their daddy issues later. Or, it might be some kind of clue they're going to remember conveniently at a crucial point. 
Be careful with this. Your reader doesn't start being as interested in your character as you are -- they probably don't care how wonderful Joe is as a six year old. Even if it is a major conflict later. They don't know Joe. Why should they care?
It's also confusing to begin your reasder with one thing (little child, crazy mother, drunk father) and then for the rest of the novel something else (morally-torn adolescent battles with the forces of evil). Start as you mean to go on, it's more honest.