Mobile storage devices come in many shapes, sizes and capacity, but they can be broadly categorized into two: flash-based and hard disk-based. Flash memory refers to solid-state, non-volatile memory chips, while disk-based storage uses spinning magnetic disk platters to store information.

Flash memory based storage devices can be further categorized into two: the USB flash drives (also known as thumb drives or USB drives) and flash memory cards. USB flash drives are small, solid-state devices (which means there are no moving parts) that look like key fobs, and they use type A USB 1.1 or 2.0 interfaces, which allow users to mount them to a USB port. USB flash drives work with most operating system and are hot swappable, meaning they can be removed from a computer without rebooting it. Prices and capacity, from 128 MB up to 8 GB, are directly related.

Memory cards are postage stamp-size storage devices used in personal digital assistants, MP3 players, video game consoles, digital cameras and laptops. Like the USB flash drives, they also use flash memory. Memory cards as also non-volatile (which means that it retains data even without power), and removable. They also come in several formats; among them are Compact Flash, Multi Media Card, Reduced Sized MMC, Secure Digital (SD), SmartMedia Card, xD-Picture Card and Memory Stick. Capacity for memory cards range from 32 MB to 8 GB. Hard disk-based mobile storage solutions are hard disk-based; therefore they have bigger capacities, starting from 80 gigabytes up to 1 terabyte. These devices can be connected to the computer via a USB interface or FireWire (IEEE 1394).

Shy away from any that offers only USB 1.1 interface, as it will be slower than a spelling bee of stutterers. When choosing one, bear in mind that you should balance your choice between the drive’s capacity, reliability and price.