A CompactFlash (CF) card is a popular memory card developed in 1994 that uses flash memory to store data on a very small card. A CompactFlash card makes data easy to add to a wide variety of computing devices, including digital cameras and music players, desktop computers, personal digital assistants (PDAs), digital audio recorders, and photo printers. 
 

Because flash is nonvolatile memory, stored data is retained when a device's power source is turned off or lost. CF cards feature solid-state construction, which makes them much more rugged than most traditional storage devices. The operating shock rating (basically, what height can you drop them from and have them still work) for CF cards is 2,000 Gs compared to a 100-200 G rating for the mechanical drive of the typical portable computing device. This translates to a drop to the floor from 10 feet, as compared to a single foot for the mechanical disk drive.