SD Standards Family
The success and pervasiveness of SD standards has given rise to countless devices, applications and services. The SD Association provides a convenient classification system below to communicate usage and features for SD standard type and size for host devices.
Note that the universally known and used SD memory cards are classified as “removable RAM” and feature three capacities: SD, SDHC and SDXC standards. The removable RAM classification also includes a category for optional content security features, which enable SD memory cards to be used as storage for copyright-protected audio, video and books. The Association further defines SD standards into an input/output (I/O) classification. SDIO card applications use the pervasive SD slot included in most consumer electronics for extended device capabilities instead of memory card storage. SDIO extends device capabilities to include a range of capabilities including Internet service, GPS and camera capabilities.