SD card

SD card
	From top to bottom: SD, miniSD, microSD
Media type	Memory card
Capacity	SD: Up to 2 GB; SDHC: Up to 32 GB; SDXC: Up to 2 TB; SDUC: Up to 128 TB;
Block size	Variable
Read mechanism	Default: Up to 12.5 MB/s; High-speed: Up to 25 MB/s; UHS-I: Up to 104 MB/s; UHS-II: Up to 312 MB/s; UHS-III: Up to 624 MB/s; Express: Up to 3940 MB/s;
Developed by	SD Association
Dimensions	Standard:; 32×24×2.1 mm (1.260×0.945×0.083 in); 1,612.8 mm3 (0.09842 cu in); Mini:; 21.5×20×1.4 mm (0.846×0.787×0.055 in); 602 mm3 (0.0367 cu in); Micro:; 15×11×1 mm (0.591×0.433×0.039 in); 165 mm3 (0.0101 cu in);
Weight	Standard: ~2 g; Mini: ~0.8 g; Micro: ~0.25 g;
Extended from	MultiMediaCard
Released	August 1999

The SD card is a proprietary, non-volatile, flash memory card format developed by the SD Association (SDA). They come in three physical forms: the full-size SD, the smaller miniSD (now obsolete), and the smallest, microSD. Owing to their compact form factor, SD cards have been widely adopted in a variety of portable consumer electronics, including digital cameras, camcorders, video game consoles, mobile phones, action cameras, and camera drones.

The format was introduced 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 several enhancements including a digital rights management (DRM) feature, a more durable physical casing, and a mechanical write-protect switch. These improvements, combined with strong industry support, contributed to its widespread adoption.

To manage licensing and intellectual property rights, the founding companies established SD-3C, LLC. In January 2000, they also formed the SD Association, a non-profit organization responsible for developing the SD specifications and promoting the format. As of 2023, the SDA includes approximately 1000 member companies. The association uses trademarked logos owned by SD-3C to enforce compliance with official standards and to indicate product compatibility.