Linux Operating System Distributions:
Linux can be freely redistributed. The user can obtain it in a variety of ways. Various individuals and organizations package Linux, often combining it with free or proprietary applications. Such a package that includes all the software needed to install and run Linux is called a Linux distribution.
Caldera, Red Hat, Slackware and SuSE are packaged by commercial companies that get profit by selling Linux-related products and services. The user can download these distributions from the respective companies web sites or make additional copies of a Linux distribution. Debian GNU/Linux is a product of volunteer effort conducted under auspices of Software In The Public Interest, Inc.