Secure Digital cards, a type of flash memory, were developed by SanDisk, Matsushita, and Toshiba as a potential replacement for the memory stick. Rugged, small and light, they work best for devices that require high storage capacity and portability. As portable electronic devices continue to come with increased functionality, SD cards also continue to improve in speed and storage capacity. SD Cards have no moving parts, which means that if they are bumped or dropped they are much less likely to break or lose data. The NAND storage is resilient and does not wear easily; data can be written and rewritten thousands of times in the lifetime of the card. Manufacturers use a variety of flash memory technologies with varying speeds to create cards. To differentiate between them, the SD Association assigned classes to these speeds of 2, 4, 6 and 10. Each class represents the minimum write speed of the card in megabytes per second. These classes matter most for those wishing to record and save real-time video. Writer Bio
