Slackware was originally derived from the Softlanding Linux System (SLS), the most popular of the original Linux distributions and the first to offer a comprehensive software collection that comprised more than just the kernel and basic utilities.
Being a student at that time, Patrick Volkerding was asked by his artificial intelligence professor at the Minnesota State University Moorhead (MSUM) to make SLS installations for the computer lab. First Volkerding made notes on bug fixes and modifications of the system's configuration, to be applied after the installation was complete. Later he incorporated the changes directly into the SLS install disks "so that new machines would have these fixes right away". He changed parts of the original SLS installation scripts and added a mechanism that installed important packages like the shared libraries and the kernel image automatically.
Volkerding had no intentions to provide his modified SLS version for the public, assuming that "SLS would be putting out a new version that included these things soon enough". However, seeing that this was not the case and that many SLS users were asking on the Internet for a new SLS release, he made a post titled "Anyone want an SLS-like 0.99pl11A system?", which he received a lot of response for. As also his friends at MSUM urged him to put his SLS modifications onto an FTP server, he made them publicly available on one of the university's anonymous FTP servers. This first Slackware release, version 1.00, was distributed on July 16, 1993, being supplied as 24 3Ż" floppy disk images.
Version 2.1, released in October 1994, already consisted of 73 floppy disks, showing the rapid growth of the distribution.
With version 3.0, released in November 1995, Slackware made the transition to the Executable and Linkable Format (ELF). It was also the first release offering a CD-ROM based installation.
In 1999, Slackware's release number jumped from 4 to 7. Patrick Volkerding explained this as a marketing effort to show that Slackware was as up-to-date as other Linux distributions, many of which had release numbers of 6 at the time, and Volkerding expected them to reach version 7 by the time of the jump.
In 2005, the GNOME desktop environment was removed from the pending future release (starting with 10.2), and turned over to community support and distribution. The removal of GNOME was seen by some in the Linux community as significant because the desktop environment is found in many Linux distributions. In lieu of this, several community-based projects began offering complete GNOME distributions for Slackware such as Ximian and LinuxSalute.
Unfortunately, at the time of this writing, the Slackware website is down: Slackware.com. Please keep checking until it comes back up!