Knoppix is a Linux distribution that can be run from a cd-rom without having to be installed to a hard drive.

It can be installed to a hard drive if desired.

It is based off the Debian distribution.

It seems to be becoming quite popular.

The best English site for information about Knoppix seems to be www.knoppix.net

The official site for Knoppix is Klaus Knopper's website: www.knoppix.org