What is a sd card ?

Secure Digital (SD) is a non-volatile memory card format developed by Matsushita, SanDisk, and Toshiba for use in portable devices. Today it is widely used in digital cameras, handheld computers, PDAs, mobile phones, GPS receivers, and video game consoles. Standard SD card capacities range from 4 MB to 4 GB, and for high capacity SDHC cards from 4 GB to 32 GB as of 2008.

It's a little (about 1" long amaybe 3/4" wide) plastic card which will plug into a slot in your camera, PDA, phone, PC, GPS, PS3 or whatever else you have that has the right sort of slot built in. Built into it is a flash memory chip, so once it's plugged in, you can store data on it - either to provide extra storage on a device that doesn't have enough of its own (very common in cellphones) or to make it easy to transfer data between one machine and another (cameras often use them this way).

First thing to think about when buying one is how much storage capacity (measured in gigaBytes) you need - the more you want, the more it costs.

Note also that there are related formats - things like Micro SD which work identically, but are physically smaller, and others like XD and MS which are different both in size and the electrical detail of how they work.

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