SD
Secure Digital
A type of removable flash memory card.
Like any flash memory card, it can be used for long-term storage of various types of files, including photos, videos, music, or software.
Full-size SD cards are smaller than Compact Flash, but larger than microSD, miniSD, or RS-MMC. MicroSD is the most common type of removable memory card in phones.
See: microSD
SD is the same size as MMC, but thicker. Some devices with SD slots can also accept MMC cards, but not vice-versa.
SD cards are generally faster than MMC, but use more power.
There is an extension of the SD protocol known as SDIO that allows devices other than memory cards to be used in SD slots, such as cameras or wi-fi adapters.
See: SDIO
Last updated Sep 3, 2021 by Rich Brome
Editor in Chief Rich became fascinated with cell phones in 1999, creating mobile web sites for phones with tiny black-and-white displays and obsessing over new phone models. Realizing a need for better info about phones, he started Phone Scoop in 2001, and has been helming the site ever since. Rich has spent two decades researching and covering every detail of the phone industry, traveling the world to tour factories, interview CEOs, and get every last spec and photo Phone Scoop readers have come to expect. As an industry veteran, Rich is a respected voice on phone technology of the past, present, and future.
