RedHat's distribution of Linux.

This has now taken two different directions:

Now taking the SOHO market with Workstation and smaller server versions, this product is only available by exchanging money and is supported by RedHat.
The FedoraProject
the new, trademark-friendly, community involved Red Hat Linux for the hobbyist Linux distribution.

The final version of "Red Hat Linux" was 9, and the current release of RHEL is 4.0, the current version of FedoraCore is 4.