The SD card is a proprietary, non-unstable, flash Memory Wave card format developed by the SD Association (SDA). They are available three bodily forms: the complete-measurement SD, the smaller miniSD (now out of date), and the smallest, microSD. Owing to their compact form factor, SD playing cards have been widely adopted in a variety of portable client electronics, including digital cameras, camcorders, video sport consoles, cell phones, motion cameras, cognitive enhancement tool and digicam drones. The format was launched in August 1999 as Secure Digital by SanDisk, Panasonic (then known as Matsushita), and Kioxia (then a part of Toshiba). It was designed as a successor to the MultiMediaCard (MMC) format, introducing several enhancements including a digital rights management (DRM) characteristic, a extra durable physical casing, and a mechanical write-protect change. These improvements, combined with sturdy trade assist, contributed to its widespread adoption. To manage licensing and intellectual property rights, the founding firms established SD-3C, LLC. In January 2000, they also formed the SD Affiliation, a non-revenue organization liable for growing the SD specs and selling the format.

As of 2023, the SDA includes roughly 1,000 member companies. The association uses trademarked logos owned by SD-3C to enforce compliance with official standards and to point product compatibility. In 1994, SanDisk introduced the CompactFlash (CF) format, one in all the primary successful flash memory card sorts. CF outpaced several competing early codecs, including the Miniature Card and SmartMedia. However, the late nineteen nineties noticed a proliferation of proprietary codecs akin to Sony's Memory Stick and the xD-Picture 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 brand new postage stamp-sized memory card referred to as the MultiMediaCard (MMC). Whereas technically progressive, MMC adoption was gradual, and even Nokia was gradual to integrate assist for it into its mobile units. In 1999, SanDisk was approached by Panasonic (then known as Matsushita) and Kioxia (then a part of Toshiba) to develop a new format as a second-era successor to MMC.

The objective was to create a portable, high-performance memory card with integrated safety features and cognitive enhancement tool broader interoperability. Involved about dropping market share to Sony's proprietary Memory Stick, Toshiba and Panasonic saw the collaboration as an opportunity to ascertain an open, trade-backed normal. Panasonic and Toshiba, who had beforehand collaborated on the Tremendous Density Disc (a DVD precursor), reused its stylized "SD" logo for the Secure Digital (SD) card format. Anticipating the expansion of MP3 gamers, in addition they advocated for digital rights administration (DRM) help searching for to reassure content material publishers wary of piracy. The DRM system adopted-Content Safety for Recordable Media (CPRM)-had been developed earlier in partnership with IBM and Intel, and Intel and complied with the Safe Digital Music Initiative customary. Although usually cited as an element within the format's broad business support, CPRM was rarely carried out in practice. SD cards additionally featured a mechanical write-protect change, and early SD slots maintained backward compatibility with MMC cards. In accordance with SanDisk, consumer adoption was accelerated by Toshiba and Panasonic's dedication to launching suitable gadgets in parallel with the playing cards.

To support standardization and interoperability, SanDisk, Toshiba, and Panasonic introduced 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 companies and has since grown to encompass around 800 organizations worldwide. At the March 2003 CeBIT trade present, SanDisk introduced and demonstrated the miniSD card format. The SD Affiliation (SDA) adopted miniSD later that year as a small-kind-issue extension to the SD card customary, supposed primarily for use in cell phones. Nevertheless, 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 term for microSD cards. A passive adapter allows microSD cards to be utilized in customary SD card slots, maintaining backward compatibility across gadgets. The storage capacity of SD playing cards elevated steadily all through the 2010s, pushed by advances in NAND flash manufacturing and interface speeds. In January 2009, the SDA introduced the Secure Digital extended Capacity (SDXC) format, supporting up to 2 TB of storage and switch speeds as much as 300 MB/s.

SDXC playing cards are formatted with the exFAT file system by default. The primary SDXC playing cards appeared in 2010, with early models offering 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 provided SDXC playing cards in 64 and 128 GB capacities, with some fashions supporting UHS Speed Class 10 and sooner. The Secure Digital Extremely Capability (SDUC) specification, introduced in 2018, expanded most capability to 128 TB and increased theoretical transfer speeds to 985 MB/s. There are 4 outlined SD capacity standards: Commonplace Capability (SDSC), Excessive Capacity (SDHC), Prolonged Capacity (SDXC), and Ultra Capability (SDUC). Along with specifying most storage limits, these standards additionally define preferred file systems for formatting playing cards. The unique Safe Digital (SD) card was introduced in 1999 as a successor to the MMC format. The identify SD Commonplace Capacity (SDSC) was utilized later to distinguish it from newer variants.