Cookie to avoid login form

Hi, everybody,
I can’t figure out the authentication flow. In the documentation it says:

The first authentication type is Cookie . When a user successfully logs in for the first time, a session cookie is set. If this cookie has already been set, then this authentication type is successful.

What is the name and value of this cookie?

My situation is the following, I want to obtain a token through this flow but without having to fill in any login form since the user has already logged in.

Thanks in advance,