Is a autobiography fiction or nonfiction

There is a lot of ambiguity in story-telling, including in the very definition of what constitutes a story (or for that matter, a novel or novella).

Is it the length, the subject matter, the structure? These questions can become contentious; for example, in a course about the novella that I took during my MFA, my classmates, professor and I once had a half-hour argument about whether novellas are just long short stories, or whether they have some other ephemeral quality that sets them apart.

Settle any of those parameters—say length—and quickly you find exceptions (e.g. For sale: baby shoes, never worn.”) 

The definitions of “fiction” and “nonfiction” at least seem distinct and unassailable—at first glance.

Broadly speaking, there seems to be a consensus that fiction is “made up stuff” and nonfiction is “true stuff.” But on closer inspection, these distinctions begin to crumble: not to get all freshman philoso