[eluser]WanWizard[/eluser]
A users session is linked to a session_id.
To determine which session belongs to a user, this session_id is sent to the browser using a cookie. At the next request, the cookie is sent back to the server, where CI can extract the session_id from the cookie, and lookup the correct session.
If you erase your local browser data, you also delete the cookie, so CI doesn't recognize you anymore, and will generate a new session for you.
