CompactFlash (CF) card A CF card is commonly used in digital cameras and mp3 players. It is generally reliable and provides a large storage capacity from 512MB to as much as 8GB. SmartMedia card The SmartMedia card is smaller and thinner than a CompactFlash card. It is more prone to damage and has a limited storage capacity. Memory Stick The Memory Stick uses a serial interface to transfer data from the source device to the card. It is more robust and reliable than the other memory cards. MultiMediaCard (MMC) An MMC is smaller and thicker than a SmartMedia card. It has interface pins on its backside similar to memory sticks. A newer variant is the Reduced Size MultiMediaCard (RS-MMC). Its is about half the size of a regular MMC, allowing it to fit into small devices. Secure Digital (SD) card The SD card is the same size and shape as the MMC, but it has an extra locking switch on the side to prevent unauthorized reading, writing over, and deleting of data from the card. It also has a digital rights management capability that prevents it from reading from MMC devices. It has two variants: the mini-SD card intended for small electronic devices such as mobile phones and mp3 players, and the micro-SD card used in most mobile phones. | 
