The SD card is a proprietary, non-unstable, flash memory card format developed by the SD Affiliation (SDA). They are available in three physical types: the complete-size SD, the smaller miniSD (now obsolete), and the smallest, microSD. Owing to their compact form factor, SD playing cards have been broadly adopted in a wide range of portable shopper electronics, including digital cameras, camcorders, video recreation consoles, cellphones, motion cameras, and camera drones. The format was launched in August 1999 as Safe Digital by SanDisk, Panasonic (then often called Matsushita), and Kioxia (then a part of Toshiba). It was designed as a successor to the MultiMediaCard (MMC) format, introducing a number of enhancements including a digital rights management (DRM) function, a more durable physical casing, and a mechanical write-protect change. These improvements, combined with strong industry support, contributed to its widespread adoption. To manage licensing and mental property rights, the founding companies established SD-3C, LLC. In January 2000, in addition they formed the SD Affiliation, a non-revenue group responsible for growing the SD specs and promoting the format.

As of 2023, the SDA includes roughly 1,000 member companies. The affiliation makes use of trademarked logos owned by SD-3C to implement compliance with official requirements and to point product compatibility. In 1994, SanDisk launched the CompactFlash (CF) format, one among the first successful flash memory card types. CF outpaced several competing early formats, together with the Miniature Card and SmartMedia. Nonetheless, the late 1990s noticed a proliferation of proprietary formats such as Sony's Memory Stick and the xD-Image Card from Olympus and Fujifilm, leading to a fragmented memory card market. To handle 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 modern, MMC adoption was gradual, and even Nokia was gradual to combine assist for it into its cell devices. In 1999, SanDisk was approached by Panasonic (then often called Matsushita) and Kioxia (then part of Toshiba) to develop a brand new format as a second-technology successor to MMC.

The aim was to create a portable, excessive-efficiency memory card with integrated safety features and broader interoperability. Involved about losing market share to Sony's proprietary Memory Wave Routine Stick, Toshiba and Panasonic saw the collaboration as a possibility to establish an open, industry-backed commonplace. Panasonic and Toshiba, who had previously 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 players, additionally they advocated for digital rights management (DRM) support in search of to reassure content material publishers wary of piracy. The DRM system adopted-Content material Safety for Recordable Media (CPRM)-had been developed earlier in partnership with IBM and Intel, and Intel and complied with the Secure Digital Music Initiative commonplace. Though typically cited as an element within the format's broad business help, CPRM was rarely carried out in practice. SD playing cards additionally featured a mechanical write-protect change, and early SD slots maintained backward compatibility with MMC playing cards. In accordance with SanDisk, consumer adoption was accelerated by Toshiba and Panasonic's commitment to launching appropriate gadgets in parallel with the cards.

To assist standardization and interoperability, SanDisk, Toshiba, and Panasonic introduced the creation of the SD Affiliation (SDA) on the January 2000 Shopper Electronics Show (CES). Headquartered in San Ramon, California, the SDA initially included 30 member companies and has since grown to encompass around 800 organizations worldwide. At the March 2003 CeBIT commerce present, SanDisk introduced and demonstrated the miniSD card format. The SD Association (SDA) adopted miniSD later that yr as a small-type-factor extension to the SD card standard, meant primarily to be used in cell phones. However, the format was largely phased out by 2008 following the introduction of the even smaller microSD card. TransFlash identify stays in common use as a generic time period for microSD playing cards. A passive adapter permits microSD playing cards to be utilized in commonplace SD card slots, maintaining backward compatibility throughout units. The storage capacity of SD playing cards elevated steadily throughout the 2010s, pushed by advances in NAND flash manufacturing and interface speeds. In January 2009, the SDA introduced the Safe Digital extended Capability (SDXC) format, supporting up to 2 TB of storage and switch speeds up to 300 MB/s.

SDXC cards are formatted with the exFAT file system by default. The first SDXC cards appeared in 2010, with early fashions offering capacities of 32 to sixty four GB and browse/write speeds of several hundred megabits per second. Client adoption accelerated as digital cameras, smartphones, and card readers gained SDXC compatibility. By 2011, manufacturers offered SDXC playing cards in 64 and 128 GB capacities, with some models supporting UHS Velocity Class 10 and sooner. The Safe Digital Extremely Capacity (SDUC) specification, announced in 2018, expanded most capacity to 128 TB and elevated theoretical transfer speeds to 985 MB/s. There are 4 outlined SD capability standards: Normal Capability (SDSC), High Capability (SDHC), Extended Capacity (SDXC), and Extremely Capacity (SDUC). Along with specifying maximum storage limits, these standards also outline most well-liked file programs for formatting cards. The original Safe Digital (SD) card was launched in 1999 as a successor to the MMC format. The title SD Standard Capacity (SDSC) was utilized later to tell apart it from newer variants.