The profile picture is the image that's displayed on your profile page. You can change it as often as you'd like. (File formats accepted: GIF, JPG or PNG)
Click and drag a square below to match how you want your picture cropped. A preview of your cropped picture will appear in the box on the right. When you are happy with the preview, click 'Create your avatar'. This cropped image will be used throughout the site as your avatar.