Summit Evergreen uses Gravatars for all user avatars.
Gravatars are a free service that uses your email address, to retrieve your custom avatar from the Gravatar site.
Don’t have an avatar? Sign up here, for free.
An “avatar” is an image that represents you online—a little picture that appears next to your name when you interact with websites.
A Gravatar is a Globally Recognized Avatar. You upload it and create your profile just once, and then when you participate in any Gravatar-enabled site, your Gravatar image will automatically follow you there.