grml is a Debian-based Live-CD. It includes a collection of GNU/Linux software especially for users of texttools and system administrators. grml provides automatic hardware detection. You can use grml for example as a rescue system, for analyzing systems/networks or as a working environment. It is not necessary to install anything to a harddisk, you don't even need a harddisk to run it, unless you want to (use grml2hd for this). Due to on-the-fly decompression grml includes about 2.1 GiB of software and documentation on the CD.
Whereas grml is meant of use on 32 bit systems, grml64 provides support for 64 bit platforms. It is based on the amd64 port of Debian.