key relationships

[Thomas Nyman]

Hello all

I have studied the gnupg handbook and read the man pages as well however 
there is a small matter I dont comprehend.

Once I create a key I then have a public and private (secret) key. If I 
wish to sign mails that's all I need. If I wish to encrypt to others I need 
their public key.

When I "Import" a key it is added to my keyring.

However, lets say I wish to have to encryption keys, i.e I create another 
public and secret key. I'm not sure exactly how to handel this. It seems 
the easiest way would be if you could maintain two seperate keyrings, but 
how that is done I havent really been able to figure out.

I have noticed postings discussing sub-keys. But I must confess I don't 
quite understand what a sub-key is. When I do a list-keys command what does 
the "sub" part of the output stand for?

regards
Thomas