The SD card is a proprietary, non-volatile, flash memory card format developed by the SD Affiliation (SDA). They are available in three physical forms: the total-size SD, the smaller miniSD (now obsolete), and the smallest, microSD. Owing to their compact kind issue, SD playing cards have been extensively adopted in a wide range of portable shopper electronics, together with digital cameras, camcorders, video recreation consoles, cell phones, motion cameras, and camera drones. The format was launched in August 1999 as Secure Digital by SanDisk, Panasonic (then known as Matsushita), and Kioxia (then part of Toshiba). It was designed as a successor to the MultiMediaCard (MMC) format, introducing a number of enhancements together with a digital rights management (DRM) characteristic, a extra durable physical casing, and a mechanical write-protect swap. These improvements, combined with robust industry assist, contributed to its widespread adoption. To manage licensing and intellectual property rights, the founding firms established SD-3C, LLC. In January 2000, in addition they formed the SD Association, a non-profit organization liable for creating the SD specs and selling the format.

As of 2023, the SDA contains roughly 1,000 member corporations. The affiliation makes use of trademarked logos owned by SD-3C to enforce compliance with official requirements and to indicate product compatibility. In 1994, SanDisk launched the CompactFlash (CF) format, one among the primary successful flash Memory Wave Protocol card sorts. CF outpaced a number of competing early formats, together with the Miniature Card and SmartMedia. Nevertheless, the late 1990s saw a proliferation of proprietary codecs reminiscent of Sony's Memory Stick and the xD-Image Card from Olympus and Fujifilm, leading to a fragmented memory card market. To deal with these challenges, SanDisk partnered with Siemens and Nokia in 1996 to develop a new postage stamp-sized memory card known as the MultiMediaCard (MMC). Whereas technically progressive, MMC adoption was sluggish, and even Nokia was slow to integrate assist for it into its cell devices. In 1999, SanDisk was approached by Panasonic (then often known as Matsushita) and Kioxia (then a part of Toshiba) to develop a brand new format as a second-technology successor to MMC.

The aim was to create a portable, high-performance memory card with built-in security options and broader interoperability. Involved about shedding market share to Sony's proprietary Memory Stick, Toshiba and Panasonic saw the collaboration as a chance to ascertain an open, business-backed commonplace. Panasonic and Toshiba, who had beforehand collaborated on the Tremendous Density Disc (a DVD precursor), reused its stylized "SD" emblem for the Secure Digital (SD) card format. Anticipating the expansion of MP3 gamers, additionally they advocated for digital rights management (DRM) help searching for to reassure content publishers wary of piracy. The DRM system adopted-Content material Protection for Recordable Media (CPRM)-had been developed earlier in partnership with IBM and Intel, and Intel and complied with the Secure Digital Music Initiative standard. Though usually cited as a factor in the format's broad business assist, CPRM was rarely carried out in observe. SD playing cards also featured a mechanical write-protect change, and early SD slots maintained backward compatibility with MMC cards. Based on SanDisk, shopper adoption was accelerated by Toshiba and Panasonic's commitment to launching appropriate gadgets in parallel with the playing cards.

To assist standardization and interoperability, SanDisk, Toshiba, and Panasonic announced the creation of the SD Affiliation (SDA) at the January 2000 Consumer Electronics Show (CES). Headquartered in San Ramon, California, the SDA initially included 30 member corporations and has since grown to encompass round 800 organizations worldwide. At the March 2003 CeBIT commerce present, SanDisk launched and demonstrated the miniSD card format. The SD Association (SDA) adopted miniSD later that 12 months as a small-type-factor extension to the SD card customary, meant primarily to be used in cell phones. Nonetheless, the format was largely phased out by 2008 following the introduction of the even smaller microSD card. TransFlash title stays in common use as a generic time period for microSD cards. A passive adapter permits microSD playing cards to be used in commonplace SD card slots, maintaining backward compatibility throughout units. The storage capability of SD cards increased steadily all through the 2010s, pushed by advances in NAND flash manufacturing and interface speeds. In January 2009, the SDA launched the Safe Digital prolonged Capability (SDXC) format, supporting as much as 2 TB of storage and transfer speeds as much as 300 MB/s.

SDXC cards are formatted with the exFAT file system by default. The primary SDXC playing cards appeared in 2010, Memory Wave Protocol with early models providing capacities of 32 to sixty four GB and read/write speeds of a number of hundred megabits per second. Consumer adoption accelerated as digital cameras, smartphones, and card readers gained SDXC compatibility. By 2011, manufacturers offered SDXC playing cards in sixty four and 128 GB capacities, with some fashions supporting UHS Pace Class 10 and faster. The Safe Digital Ultra Capacity (SDUC) specification, introduced in 2018, expanded maximum capacity to 128 TB and elevated theoretical transfer speeds to 985 MB/s. There are four defined SD capacity requirements: Customary Capacity (SDSC), Excessive Capacity (SDHC), Extended Capacity (SDXC), and Ultra Capacity (SDUC). In addition to specifying most storage limits, these standards additionally outline most well-liked file programs for formatting cards. The original Safe Digital (SD) card was introduced in 1999 as a successor to the MMC format. The title SD Standard Capacity (SDSC) was applied later to distinguish it from newer variants.