An Avatar is a personal respresentation of yourself in icon format.  Having a small image that relates to you is a great way for people to identify you or with you.

Wikipedia Definition for Avatar

You can upload a small image at least 50px wide by 50px in height.  If the Avatar is going to be scaled is will maintain the same aspect ratio. 

You can upload or change your Avatar at the following url:

http://www.giveness.com/member/admin/EditAvatar.aspx