SD Card

(Secure Digital Memory Card) A family of compatible and very popular flash memory cards used primarily for camera and extra phone storage. Introduced in 1999 by Panasonic, Toshiba and SanDisk as the successor to the MultiMediaCard (see MMC), the SD technology is managed by the SD Association (www.sdcard.org). SD uses NAND flash technology (see flash memory).

Capacities have reached 400GB for microSD cards and 512GB for the full size card. SD cards support various write speeds for video recording (see SD card classes). Although SD cards support copyright protection (the "Secure" in SD), they were never much used for that purpose (see CPRM). See Video HD, Eye-Fi and SDIO card.

SD Express - More Speed
In 2018, SD Express was introduced, which supports additional interfaces and higher speeds while keeping backward compatibility with the billions of SD hosts in the world. See SD Express.

MicroSD - MiniSD - Full-Size

With storage up to 400GB, the tiny 15x11x1mm microSD card (left) is the most popular, and it obsoleted the miniSD format. The full-size 32x24x2mm card is available up to 512GB. Adapters let microSDs plug into full-size slots (see microSD). (Images courtesy of SanDisk Corporation, www.sandisk.com)

SDHC, SDXC, SDUC

As storage increased, HC, XC and UC formats were introduced to accommodate the larger capacities. All newer-format SD slots accept the older cards. See FAT32 and exFAT. (Images courtesy of SanDisk Corporation, www.sandisk.com)

Year Maximum FileFormatInto Capacity System SD 1999 2GB FAT16 SDHC 2006 32GB FAT32 SDXC 2009 2TB exFAT SDUC 2018 128TB exFAT