[keycloak-user] Using access token

This page mentions basics about the access token and how it contains information about the user: http://keycloak.github.io/docs/userguide/html/Overview.html#d4e54 But its a bit vague about how to get access to this information. e.g. in my client app I might want to access the user's email address. Is there documentation on how to do this? Tim