There are many different types of flash memory cards that can be used with cameras and other storage devices. Almost all of them use basically the same technology, but they differ in ways that make them incompatible with each other. Some use different communication methods, and some are simply the wrong size. Here are some of the most popular memory card types, and the ones that you should know in order to make an informed decision.
CompactFlash, or CF cards, were for a while the most popular card to use with digital cameras. They contain not only the memory chips, but microcontrollers as well. The capacities range from mere megabytes all the way up to 16 GB. There are two different types of CF cards. Cameras built for type I cannot use type II - however, cameras built for type II can use both. Be sure to check before you invest in an expensive high capacity card. Lots of advanced cameras use CF instead of one of the alternatives.
The Secure Digital (SD) card has taken over the market share when it comes to compatibility. Nowadays, the huge majority of cameras use SD cards. Unless you are going to buy a high-grade professional camera, it is likely that you won't have many other choices besides SD. Modern SD cards reach sizes up to 2 or even 4 GB, with most cards sold being around 512 MB or 1 GB. Recent cards have achieved much higher transfer rates, around 20 MB/s.
The SDHC card has evolved from the SD card, and uses some of the same specifications. It is modified for much larger capacities, all the way up to 32 GB. Many modern cameras support SDHC since it isn't too radically different from its predecessor. But, it is still a fairly new technology, and you should make sure that your camera or your card reader are build to handle it. You can sometimes even find updates that allow for SDHC functionality, since most of the differences are in the software rather than the hardware.
If you plan to get into the world of digital cameras and start enjoying the convenience of taking photos without film, then you'll definitely need at least one good memory card with you. So consider the different high-tech options that are available to you, and consider your own needs (such as how many pictures you want to store at one time), and you'll be able to get the perfect memory card.
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