Linux

Linux is a type of computer operating system - such as Windows or Mac OS.

Regarding DH Box

DH Box creates a virtual computer where DH tools are installed and configured; the operating system for this virtual computer is Linux.

There are many reasons that make Linux a more suitable operating system for DH Box than Windows or Mac - one major reason being that the command line is utilized much more prominently by Linux users than Windows or Mac users. For DH Box, the command line is invaluable - it facilitates the automatic install of DH tools on this virtual computer as well as in facilitating DH Box users' interaction with certain DH tools (such as NLTK).

Wikipedia

For more information, check out the Wikipedia entry on the Linux operating system: http://en.wikipedia.org/wiki/Linux