A flash card is a mini storage device that uses a flash memory chip to store data. Flash cards can be as small as the size of a wafer, while capacity can range anywhere from 8MB to several gigabytes.

Flash cards are highly reliable because there are no moving parts. Flash memory is also fairly fast because it erases and writes in blocks, rather than byte by byte as did its predecessor, EEPROM. Flash memory is erased by electrical charges or flashes, hence the name, flash card.

Flash cards are common in many of today's devices, providing expanded storage for products that include digital cameras, Personal Digital Assistants (PDAs), MP3 players, and more.

The only drawback of flash cards is that the industry does not use a standardized format. Therefore flash cards are most often not interchangeable between devices. A product that utilizes a flash card will specify which model of flash card to get. Different models are formatted to meet the specifications of different manufacturers and devices. Once you find the model of flash card your device requires, you can choose the capacity. But if you own more than one device that uses a flash card, you might need a different flash card for each device you own, depending on the format.

Some flash card formats include: CompactFlash Type I & II (CF), Microdrive (MD), Memory Stick (MS), MagicGate (MG), SmartMedia (SM), MultiMedia Card (MMC), Secure Digital (SD), ATA Flash Card, PC Card Hard Drive, and xD Picture Card (xD).

For cross-format compatibility, devices that offer support for CompactFlash and SmartMedia might be something to consider, as these two formats command a large percentage of the market. However, if you favor Sony products, the Memory Stick/MagicGate format is used almost exclusively for their devices.

While all products that use flash cards have cable or wireless connectivity to offload the data in the flash card to your PC, flash card readers provide another solution. The advantage of a reader is that it stays permanently connected to your PC through the USB or IEEE firewire port. You simply eject the flash card from the device and slide it into the reader, rather than having to bring the device to the PC and search for the device's cable. Early readers only handled one or two flash card formats, but now various models are designed to read most if not all flash formats.

Flash cards are being incorporated into more and more devices as an excellent solution to expanded storage, and will likely be seen in countless products of the future.