Knoppix

Knoppix, or KNOPPIX ( /kᵊˈnɒpɪks/ k-NOP-iks), is an operating system based on Debian designed to be run directly from a CD / DVD (Live CD) or a USB flash drive (Live USB), one of the first of its kind for any operating system. Knoppix was developed by Linux consultant Klaus Knopper. When starting a program, it is loaded from the removable medium and decompressed into a RAM drive. The decompression is transparent and on-the-fly.