When choosing data storage for gadgets, it is important to choose one that's accesible and convenient for you to use. Some built-in card readers can only read certain types of memory cards so it's advisable that you check the compatibility before purchasing anything. The most common cards that are in the market nowadays are the MMC, memory stick and the SD card. Each card has a certain purpose and feature and some of them only work for cetain gadgets like the memory stick which only works for Sony products. Whichever it is that you choose, make sure everything is compatible with one another.