One of the earlier Linux distributions, Slackware Linux or Slackware was developed in 1993 by Patrick Volkerding as a very similar operating system to Unix. It is based on the Softlanding Linux System and due to its stability and simplicity, is the basis for other Linux distributions.
One of the most notable Slackware-based distributions is SUSE Linux. As of November 2013, version 14.1 is the most current release of Slackware. It is designed for both IA-32 and x86-64 architectures, but a port for the ARM architecture is also available. It is free and considered to be open source software, however, no public code repository or official bug tracking is maintained.