Knoppix, or KNOPPIX, is a Linux distribution based on Debian designed to be run directly from a CD / DVD. Knoppix is one of the best-known LiveDistros.
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Prior to Knoppix 3.8.2, any documents or settings a user created would disappear upon reboot. This lack of permanence made it necessary to save documents explicitly to a hard drive partition, over the network, or to some removable medium, such as a USB flash drive.