A device to which information is read and written in fixed-size blocks randomly accessible anywhere on the device.
As opposed to a CharacterDevice.
Common examples of BlockDevices are HardDisks, optical drives (CD/DVD readers/writers), memory-card readers (for e.g. SD cards, CF cards, xD cards) and USB storage devices (USB KeyDrives or external hard drives/optical drives).
See also DeviceDriver
11 pages link to BlockDevice: