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Our online glossary is here to help you make sense of the terminology used in the cell phone industry. It covers mobile technologies, such as 3G and 4G, and even includes a bit of information on smartphone operating systems and the companies that make the cell phones and other mobile technology devices we all use.

What is "SD"?

Secure Digital cards, most commonly referred to simply as SD cards, are flash memory based media cards based on a standard developed by the Secure Digital Card Association. The SD design was based on the older MMC format, but has a number of differences. SD cards are 32mm x 24mm in size, or roughly the same as a typical postage stamp.

Also known as: "Secure Digital"

Referred to by: microSD, miniSD, MMC

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