RPM (Red Hat Package Management) files are used for distributing and installing packages under Red Hat, Fedora and related Linux systems.

Sources of RPMs:

• RPM Fusion is a repository of RPM packages that Red Hat doesn't want to ship with Red Hat or Fedora.
  

RPM references:

• Maximum RPM:  Taking the Red Hat Package Manager to the limit  While this reference is not a good starting place for the RPM newbie, it is chock full of detailed information on tweaking RPM settings for the user that has a handle on the basics.  For myself, it was invaluable in learning about the %setup macro and how to modify its operation.