I’m running CentOS, (Community Enterprise OS).
It is a community version of Red Hat Linux. The Red Hat distribution is aimed at a corporate customer user base. Red Hat customers pay Red Hat for support of Linux.
The CentOS team is an organization unto itself, though it has ties with Red Hat (recent changes brought them closer). They call Red Hat the “upstream vendor”. CentOS basically takes Red Hat’s distribution, source code and all, and removes the Ret Hat branding and substitute CentOS branding, and builds their distribution from that. The CentOS distribution is available free of charge - but the caveat is there’s no support available to purchase. The CentOS customer must get by on their own.
Red Hat/CentOS comes with Mozilla Firefox as its default browser.
It's not the bleeding edge, by any means, but it's stable and reliable. The less blood, the better.