A LiveDistro is a distribution of an operating system on some bootable storage medium. LiveDistro is more commonly referred to as "liveCD" because compact discs (CD) have been the most common format. However, as portable storage devices proliferate, LiveDistros may be stored on an ever-increasing list of media, such as DVDs, floppy disks, iPods and jump drives. LiveDistros are available for many operating systems, although they are most often Linux-based. MEPIS and Knoppix are two common examples.
The word "live" refers to the immediacy of operation. The OS and applications run from the portable media. No changes are made to the host computer system unless initiated by the user. Files that would, ordinarily, have been written to the hard drive are stored in temporary memory instead. Afterwards, when the host system is rebooted, its previous state is restored. In fact, you can use a LiveDistro in a computer that has no hard drive installed at all. A LiveDistro may include an installation utility, in case that is desired.
LiveDistros are used in several ways. For example, they allow users to carry their chosen operating systems and their own applications and data when traveling or using public computers. This capacity is useful not only for people with limited technical skills, who are often more comfortable if the interface is familiar, but also for the technically savvy, who are often quite particular about plug-ins, bookmarks or other customizations. LiveDistros are also used quite frequently as a way to try out a new operating system without uninstalling the old one or to maintain a ready back-up source in case of system failure.