Question

When someone writes about his or her own life, what is it called?

Answer 1

the definition of an autobiography is:

autobiography |ˌôtəbīˈägrəfē|
noun ( pl. -phies)
an account of a person's life written by that person : he gives a vivid description of his childhood in his autobiography.
• such writing as a literary genre.

Answer 2

an autobiography. and if someone else is writing about another persons life , that's a biography