Help - Character Details
From your account page, you can enter in various details about your character, including their physical appearance, personality, and backstory.
These are all optional, and except for your character's Motivation, have no effect on gameplay. They are available to you for your entertainment (and possibly the entertainment of others :P)
Your character's Motivation is the only detail which has an impact on gameplay, though small. It is part of the Personality details.