The SD card is a proprietary, non-risky, flash memory card format developed by the SD Association (SDA). They are available in three physical kinds: the complete-dimension SD, the smaller miniSD (now out of date), and the smallest, microSD. Owing to their compact form issue, SD playing cards have been widely adopted in a wide range of portable consumer electronics, including digital cameras, camcorders, video game consoles, cell phones, action cameras, and camera drones. The format was launched in August 1999 as Secure Digital by SanDisk, Panasonic (then often 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) feature, a extra durable bodily casing, and a mechanical write-protect change. These enhancements, combined with robust trade help, contributed to its widespread adoption. To handle licensing and mental property rights, the founding corporations established SD-3C, LLC. In January 2000, in addition they formed the SD Association, a non-profit organization chargeable 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 of the primary profitable flash memory card varieties. CF outpaced several competing early codecs, together with the Miniature Card and SmartMedia. Nonetheless, the late nineties saw a proliferation of proprietary codecs such as Sony's Memory Wave System Stick and the xD-Picture Card from Olympus and Fujifilm, leading to a fragmented Memory Wave 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 called the MultiMediaCard (MMC). While technically modern, MMC adoption was sluggish, and even Nokia was slow to integrate support for it into its cell gadgets. In 1999, SanDisk was approached by Panasonic (then often known as Matsushita) and Kioxia (then part of Toshiba) to develop a brand new format as a second-generation successor to MMC.

The aim was to create a portable, high-performance memory card with integrated safety options and broader interoperability. Involved about losing market share to Sony's proprietary Memory Stick, Toshiba and Panasonic noticed the collaboration as a chance to determine an open, business-backed commonplace. Panasonic and Toshiba, who had beforehand collaborated on the Super Density Disc (a DVD precursor), reused its stylized "SD" brand for the Secure Digital (SD) card format. Anticipating the growth of MP3 players, they also advocated for digital rights management (DRM) assist looking for to reassure content material publishers cautious 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 Safe Digital Music Initiative normal. Though usually cited as an element within the format's broad industry help, CPRM was rarely applied in practice. SD cards also featured a mechanical write-protect change, and early SD slots maintained backward compatibility with MMC cards. In response to SanDisk, client adoption was accelerated by Toshiba and Panasonic's commitment to launching appropriate devices in parallel with the cards.

To support standardization and Memory Wave 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 firms and has since grown to encompass round 800 organizations worldwide. On the March 2003 CeBIT commerce present, SanDisk introduced and demonstrated the miniSD card format. The SD Association (SDA) adopted miniSD later that year as a small-type-issue extension to the SD card standard, meant primarily for use in cellphones. Nonetheless, the format was largely phased out by 2008 following the introduction of the even smaller microSD card. TransFlash title stays in widespread use as a generic time period for microSD cards. A passive adapter allows microSD cards to be used in standard SD card slots, maintaining backward compatibility across devices. The storage capacity of SD playing cards elevated steadily throughout the 2010s, Memory Wave System pushed by advances in NAND flash manufacturing and interface speeds. In January 2009, the SDA introduced the Secure Digital extended Capability (SDXC) format, supporting up to 2 TB of storage and switch speeds as much as 300 MB/s.

SDXC cards are formatted with the exFAT file system by default. The first SDXC cards appeared in 2010, with early models offering capacities of 32 to 64 GB and skim/write speeds of a number of hundred megabits per second. Client adoption accelerated as digital cameras, smartphones, and card readers gained SDXC compatibility. By 2011, manufacturers supplied SDXC playing cards in sixty four and 128 GB capacities, with some models supporting UHS Speed Class 10 and quicker. The Secure Digital Extremely Capability (SDUC) specification, introduced in 2018, expanded maximum capacity to 128 TB and increased theoretical switch speeds to 985 MB/s. There are 4 defined SD capability standards: Normal Capacity (SDSC), High Capability (SDHC), Prolonged Capacity (SDXC), and Extremely Capacity (SDUC). Along with specifying maximum storage limits, these standards additionally define most popular file systems for formatting playing cards. The unique Secure Digital (SD) card was introduced in 1999 as a successor to the MMC format. The title SD Normal Capability (SDSC) was utilized later to distinguish it from newer variants.