 "Minimal CDs" are available (for server use) that fit on a CD.Additionally, USB flash drive installations can be used to boot Ubuntu and Kubuntu in a way that allows permanent saving of user settings and portability of the USB-installed system between physical machines (however, the computers' BIOS must support booting from USB).In newer versions of Ubuntu, the Ubuntu Live USB creator can be used to install Ubuntu on a USB drive (with or without a live CD or DVD).