autobiography is fiction or not???

fiction
a. A literary work whose content is produced by the imagination and is not necessarily based on fact.
b. The category of literature comprising works of this kind, including novels and short stories.

autobiography
The biography of a person written by that person.

So fiction used to be not based on fact, but autobiography ought to be based on fact (although some people lied about their past, but that is another question. =.=``)

I hope this can help your understanding. :)

Fictitious people's autobiography is fiction.