Trying to understand CAS and SPNEGO (non interactive login)

[Development Het Baken (Netherlands)]

After a lot of research, we decided to use CAS as our SSO solution. We want a 
non-interactive login, using SPNEGO. I'm preparing for the implementation now.
I don't understand the relationship between the Browser and CAS, when the user 
logs in via Active Directory.
The CAS protocol is saying:
3.6.1. ticket-granting cookie properties
Ticket-granting cookies MUST be set to expire at the end of the client's 
browser session.

Does this mean that a browser will open after the login? Or how does this work?

Thanks in advance,

Highschool Het Baken (Netherlands)
Development