Linux
Qoting Wikipedia1: Linux is a free and open-source, monolithic, modular (i.e., it supports the insertion and removal at runtime of loadable kernel objects), Unix-like operating system kernel available for a variety of hardware architectures (like i386 or AMD64). ISG D-ITET is using Linux on a wide range of systems, from service servers, compute cluster, staff and student workstations. The ISG D-ITET systems are set up using the Debian GNU/Linux distribution.
Configurations - Hints for configuring Linux
Applications - Using some selected Linux applications
Software - List of available software on Linux (you can also use the comandline tool sepp on the command line)
Distributions - Used distributions and other distributions.