A USB flash drive consists of a NAND-type flash memory data storage device integrated with a USB (universal serial bus) interface. USB flash drives are typically removable and rewritable, much smaller than a floppy disk (1 to 4 inches or 2.5 to 10 cm), and most USB flash drives weigh less than an ounce. Storage capacities typically range from 64 MB to 128 GB with steady improvements in size and price per gigabyte. Some allow 1 million write or erase cycles and have 10-year data retention, and are connected by and compatible with USB standards 1.1 and above.

USB flash drives offer many advantages over other portable storage devices, particularly floppy disks, or CDs - they even hold more than DVDs and BluRay Discs. They have a more compact shape, operate faster, hold much more data, have a more durable design, and operate more reliably due to their lack of moving parts. Plus they come in a wide variety of shapes, designs, and color - some quite unique - they have truly become a vanity or fashion product!

Additionally, it has become increasingly common for computers to be sold without floppy disk drives, and the new Netbooks don't have optical drives either. USB ports, on the other hand, appear on almost every mainstream PC, laptop, netbook, and handheld. These types of drives use the USB mass storage standard, supported natively by modern operating systems such as Windows, Mac OS X, Linux, and other Unix-like systems. USB drives with USB 2.0 support can also operate faster than many optical disc drives, while storing a larger amount of data in a much smaller space.

Nothing actually moves in a flash drive: the term drive persists because computers read and write flash-drive data using the same system commands as for a mechanical disk drive, with the storage appearing to the computer operating system and user interface as just another drive.

A flash drive consists of a small printed circuit board protected inside a plastic, metal, or rubberized case, robust enough for carrying with no additional protection—in a pocket or on a key chain, for example. The USB connector is usually protected by a removable cap or by retracting into the body of the drive, although it is not likely to be damaged if exposed. Most flash drives use a standard type-A USB connection allowing plugging into a port on a personal computer.

If a device has a smaller type USB connector, there are solutions to connecting the full-size USB connector. Adaptors are available, as well as USB hubs.