-A KeyDrive is basically a bit of flash memory with a [USB] interface. They're roughly as large as a thumb (so sometimes referred to as "thumb drive") and perfect for carrying one around on your keychain (hence the name "key drive"). Their capacity is commonly 128[MB], which makes them a more sensible contemporary means of transporting data than [FloppyDisk]s would be. Such data could be your various [PrivateKey]s (for [SSH], [GPG], etc) so you never need to store them on a HardDrive . You can even boot from a KeyDrive if your [BIOS] supports this. Some [LinuxDistribution]s are bootable directly from a KeyDrive, others can use a KeyDrive to make your home directory and other configuration data persistent.