Red Hat Linux was a distribution developed by Red Hat to 2004. The first version of the distribution was released on 3 November 1993 and the operating system was originally called Red Hat Commercial Linux.
It was the first distribution that took advantage of the RPM package manager, and it was the basis for many derivative distributions including Mandriva Linux and Yellow Dog Linux.
2003, Red Hat has interrupted the development of Red Hat Linux and has focused on Red Hat Enterprise Linux (RHEL), which aims to support business and commercial applications. 
Fedora, developed by the Fedora Project community with Red Hat support, is a free version of it for personal use. The official support of Red Hat Linux 9, the latest version of the system, was terminated on April 30 2004.
Today, RHEL's development company announced the new beta version of the Red Hat Enterprise Linux 7.x series.
The new release, Red Hat Enterprise Linux 7.4 Beta, includes bug fixes and some new features for the 7.x product line.
"To help the protection of the latest threats and provide a more secure platform for mission-critical applications, Red Hat Enterprise Linux 7.4 Beta introduces several new security features, including:
- Support for encryption of dedicated network drives (Network Bound Disk Encryption), a tool designed to scale down managementof disk encryption.
- Improvements to OpenSSL HTTP / 2.0, allowing the use of multiple TLS (Transport Layer Security) protocols in OpenSSL and Application-Layer Protocol Negotiation (ALPN).
- Updated possibilities control, designed to make it easier for administrators to filter the events logged by the control system, gather more information from critical events, and interpret large numbers of files.”
More information can be found in the official announcement of the issue and in the release notes. Downloads are only available through the Red Hat customer portal.
As for the rest, patience until the release CentOS the corresponding beta version.
With information from WikiPedia.
