Debian and Slackware are the two oldest distros still around, beating out Red Hat by roughly a year. They form the inspiration and, in some key ways, the basis

Debian and Slackware are the two oldest distros still around, beating out Red Hat by roughly a year. They form the inspiration and, in some key ways, the basis of many modern distros, and Debian especially created apt-get and greatly increased the number of people familiar with dependency-tracking package management. (I honestly can't find anything saying the Debian people invented dependency-tracking package management. FreeBSD's ports system might predate it. However, Debian brought the idea to more people than FreeBSD was able to.) Ubuntu still uses Debian packages, like a number of other distros, and Debian has seen other distros rise and fall. Ian Murdock therefore had a direct hand in creating core infrastructure we rely on to this day, whether we know it or not.