The SD card is a proprietary, non-unstable, flash memory card format developed by the SD Association (SDA). They come in three bodily forms: the complete-measurement SD, the smaller miniSD (now out of date), and the smallest, microSD. Owing to their compact type factor, SD cards have been extensively adopted in a wide range of portable client electronics, including digital cameras, camcorders, video sport consoles, cell phones, action cameras, and digital camera drones. The format was launched in August 1999 as Safe 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 several enhancements including a digital rights management (DRM) feature, a extra durable physical casing, and a mechanical write-protect switch. These enhancements, mixed with robust business help, contributed to its widespread adoption. To handle licensing and intellectual property rights, the founding companies established SD-3C, LLC. In January 2000, in addition they formed the SD Affiliation, a non-revenue group answerable for developing the SD specifications and selling the format.

As of 2023, the SDA consists of roughly 1,000 member companies. The affiliation makes use of trademarked logos owned by SD-3C to enforce compliance with official standards and to indicate product compatibility. In 1994, SanDisk launched the CompactFlash (CF) format, one of the first profitable flash memory card sorts. CF outpaced a number of competing early formats, together with the Miniature Card and SmartMedia. However, the late nineties noticed a proliferation of proprietary formats similar to Sony's Memory Stick and the xD-Image Card from Olympus and Fujifilm, resulting in 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 Wave card called the MultiMediaCard (MMC). While technically progressive, MMC adoption was gradual, and even Nokia was gradual to combine help for it into its mobile gadgets. In 1999, SanDisk was approached by Panasonic (then generally known as Matsushita) and Kioxia (then a part of Toshiba) to develop a brand new format as a second-era successor to MMC.

The objective was to create a portable, high-efficiency memory card with built-in safety features and broader interoperability. Concerned about shedding market share to Sony's proprietary Memory Stick, Toshiba and Panasonic noticed the collaboration as a chance to determine an open, trade-backed standard. 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 growth of MP3 gamers, additionally they advocated for digital rights administration (DRM) support looking for to reassure content material publishers cautious of piracy. The DRM system adopted-Content 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 normal. Although typically cited as an element in the format's broad business assist, CPRM was hardly ever implemented in practice. SD cards also featured a mechanical write-protect change, and early SD slots maintained backward compatibility with MMC cards. Based on SanDisk, consumer adoption was accelerated by Toshiba and Panasonic's commitment to launching suitable devices 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 Shopper Electronics Present (CES). Headquartered in San Ramon, California, the SDA initially included 30 member companies and has since grown to encompass round 800 organizations worldwide. On the March 2003 CeBIT trade show, SanDisk launched and demonstrated the miniSD card format. The SD Association (SDA) adopted miniSD later that year as a small-type-factor extension to the SD card normal, intended primarily for use in cellphones. However, the format was largely phased out by 2008 following the introduction of the even smaller microSD card. TransFlash name stays in frequent use as a generic time period for microSD cards. A passive adapter permits microSD cards to be used in standard SD card slots, maintaining backward compatibility throughout units. The storage capacity of SD cards increased steadily throughout the 2010s, driven by advances in NAND flash manufacturing and interface speeds. In January 2009, the SDA launched the Safe Digital extended Capability (SDXC) format, supporting as much as 2 TB of storage and transfer speeds up to 300 MB/s.

SDXC playing cards are formatted with the exFAT file system by default. The primary SDXC cards appeared in 2010, with early models providing capacities of 32 to 64 GB and read/write speeds of several hundred megabits per second. Client adoption accelerated as digital cameras, smartphones, and card readers gained SDXC compatibility. By 2011, manufacturers provided SDXC cards in 64 and 128 GB capacities, with some fashions supporting UHS Pace Class 10 and quicker. The Secure Digital Ultra Capacity (SDUC) specification, announced in 2018, expanded maximum capability to 128 TB focus and concentration booster increased theoretical transfer speeds to 985 MB/s. There are 4 outlined SD capacity standards: Standard Capacity (SDSC), High Capacity (SDHC), Prolonged Capacity (SDXC), and Ultra Capacity (SDUC). In addition to specifying maximum storage limits, these standards also define most popular file systems for formatting playing cards. The original Secure Digital (SD) card was launched in 1999 as a successor to the MMC format. The identify SD Customary Capacity (SDSC) was applied later to differentiate it from newer variants.