roles and inheritance

Greetings,

I'm creating roles for the first time in Postgres. Up until now,
I've only needed to grant privs to individuals. I've been going over
the documentation on this and there is a part that is not very clear
to me. It concerns inheritance. First of all, if I create the role
database_name_select and add John and Mary to it, the role
database_name_select won't inherit John and Mary's privs, will it? I
do want John and Mary to inherit the privs of the
database_name_select role. Do I set database_name_select with the
option inherit or no inherit? The implication is that roles can
inherit from other roles; is that correct?

Thanks for your help,

Carol