A Memory Stick is a removable memory card format, launched by Sony in October 1998.
Typically, a Memory Stick is used as storage media for a portable device, in a form that can easily be removed for access by a PC. For example, Sony digital cameras use Memory Sticks for storing image files. With a Memory Stick reader a user could copy the information form the stick to the PC.
The original Memory Sticks were approximately the size and thickness of a stick of chewing gum, and came in sizes from 4 MB up to and including 128 MB. This size limitation became limiting fairly quickly, so Sony introduced the now-uncommon Memory Stick Select, which was similar in concept (if not in execution) to the way in which 5.25" floppy disks used both sides of a disk. A Memory Stick Select was two (or rarely four) separate 128 MB partitions which the user could switch between using a switch on the card. This solution was fairly unpopular, but did allow for users with older Memory Stick devices to use higher-capacity flash memory. The 256 MB Memory Stick Select is still being manufactured by Lexar.