MicroSD is a format for removable flash memory cards. It is
derived from SanDisk TransFlash and is used mainly in mobile
telephones but also other portable devices This card to date
(2008) is the smallest memory card available commercially. At
11†mm ◊ 15†mm ◊ 0.7†mm (about the size of a fingernail) There
are adapters which allow a microSD card to be used in devices
intended for SD, miniSD, MemoryStick Duo and even USB cards.
However, they are not universally compatible. All Micro SD cards
above 2GB are known as Micro SDHC and the user must ensure these
cards are suitable for their device.