When a user logs into a realm, Keycloak maintains a user session for them and remembers each and every client they have visited within the session. There are a lot of administrative functions that realm admins can perform on these user sessions. They can view login stats for the entire realm and dive down into each client to see who is logged in and where. Admins can logout a user or set of users from the Admin Console. They can revoke tokens and set up all the token and session timeouts there too.