Fanfiction is stories written by fans of a particular author or series, based on characters and situations from that series. It is always not for profit, stories written by fans and posted for free on the Internet for the enjoyment of other fans.

During the late 1990s I wrote a lot of fanfiction based on Ranma 1/2 by Rumiko Takahashi. Family, work, and other responsibilities have mostly taken me away from this, though I still get back to it occasionally.
Adventures of the Troubleshooter
Solo stories featuring my Champions RPG character, a sort of poor man's Iron Man. This uses a version of the official Champions Universe for background, but the major characters in the story are original.

Episode 1: The Thing In The Box
Writing aids
Hopefully useful information for aspiring writers.

An Essay on Narrative Points of View