Aeris is a 22 year old flower merchant that grows her flowers in an old church, and lives with her mother in the Sector 5 slums. Aeris's mother isn't her real mother, her mother's husband came back from somewhere with a little baby {Aeris} 22 years ago just before he died. The Shinra Company wants to abduct Aeris for some experiments because Aeris is an Ancient. Cloud saves her and after that, Aeris joins Cloud and the others for good.
As most of you probably know, Aeris will be killed by Sephiroth at the end of disc 1. I went into the game already knowing this so, despite the temptation of using my most powerful Magic user, I kept her out of my main party. That way, I wouldn't have to put a lower level character in my party after she went. If you do use her, load her down with Materia since she is the best Magic user. Her limit breaks are almost all healing, so you don't have to put to many curative Materia on her. Also remember to keep her in the back, since you should rarely attack with her. To find out how to get Ultiate Weapon and Level 4 limit break, see the tips section.