What Is... A Headcanon?

What is... a headcanon?

A headcanon is a personal idea, a theory, or a particular belief about a piece of media. These theories are the ideas of an individual fan, even though they are not actually canon in the source material. They are their personal ideas about a character, a specific scene or about background information.

They can become canon if they get adopted into the actual source material by their creators.

Or they can become part of fanon if the headcanon attracts a bigger group of fans that like the ideas more than what canon shows them.

Headcanons can give extra information to the piece of media and just fill empty spaces or it can contradict it.