Secure Digital

Secure Digital (SD) is a type of non-volatile memory (flash memory) used in memory cards, often used in digital cameras and other compact devices needing means of storage and data transfer. SD is "managed flash memory", meaning that there is an embedded controller keeping track of what parts of the chip are reliable for data storage (since flash memory in its raw form is not very reliable).

Sizes

 * SD
 * MiniSD
 * MicroSD

Formats

 * SDHC
 * SDXC
 * SDIO

Links

 * Wikipedia article
 * Official website
 * SD Simplified Specifications
 * Exploration and Exploitation of an SD Memory Card (video)
 * SanDisk Packs 128GB Into A MicroSD Card