“Flash” Memory loosely refers to any non-volatile, rewriteable, random access memory. A Flash Drive or Thumb Drive consists of a Flash Memory chip that stores the data, a controller that manages the read/write operations, and a USB interface. Besides as an integrated unit, Flash memory also exists as distinct memory cards that can be plugged into Memory Card readers that have a USB interface. Memory card types include Compact Flash, Secure Digital, Multimedia, xD, Memory Stick, and more. These differ in their working, but offer similar functionality.