Wikipedia
CompactFlash (CF) is a flash memory mass storage device used mainly in portable electronic devices. The format was specified and the devices were first manufactured by SanDisk in 1994.
CompactFlash became the most successful of the early memory card formats, surpassing Miniature Card and SmartMedia. Subsequent formats, such as MMC/ SD, various Memory Stick formats, and xD-Picture Card offered stiff competition. Most of these cards are smaller than CompactFlash while offering comparable capacity and speed. Proprietary memory card formats for use in professional audio and video, such as P2 and SxS, are faster, but physically larger and more costly.
CompactFlash remains popular and is supported by many professional devices and high end consumer devices. As of 2014, both Canon and Nikon use CompactFlash for their flagship digital still cameras. Canon also chose CompactFlash as the recording medium for its professional high-definition tapeless video cameras. Ikegami professional video cameras can record digital video onto CompactFlash cards through an adaptor.
In 2008, a variant of CompactFlash, CFast was announced. CFast (also known as CompactFast) is based on the Serial ATA interface rather than the Parallel ATA interface used by the original CompactFlash cards.
In November 2010, SanDisk, Sony, and Nikon presented a next generation card format to the CompactFlash Association. The new format has a similar form factor to CF/CFast but is based on the PCI Express interface instead of Parallel ATA or Serial ATA. With potential read and write speeds of 1 Gbit/s (125 MByte/s) and storage capabilities beyond 2 TiB the new format is aimed at high-definition camcorders and high-resolution digital cameras, but the new cards are not backward compatible with either CompactFlash or CFast. The XQD card format was officially announced by the CompactFlash Association in December 2011.