showing that someone is speaking or writing about themselves :
The writer is deliberately personal, using the first-person pronoun throughout.
telling a story using the form "I" or "we":
The nameless first-person narrator is the focus of the story.
described by someone who was actually present somewhere or who actually experienced something, rather than by someone reporting what they said:
a collection of first-person accounts of former slaves
used to refer to a video game that you play as though you are the person in the game:
Doom is the orginal first-person shooter video game.