USB flash drive consist of a flash memory data storage device integrated with a USB(Universal Serial Bus) 1.1 or 2.0 interface. A USB flash drive s are usually removable and rewritable, and physically much smaller than a floppy disk. Average weight is less than 30g. Its storage capacity increases every year with its steady improvements in size and capacity.

USB flash drives are often used for the same purpose as floppy disks were. Smaller, faster and thousands times more capacity than floppy disk, and more durable due to lack of internal moving parts. Flash drives use the USB mass storage standard, supported by modern OS (operating system) such as Windows, Mac OS X, and other Unix-like systems USB flash drives with USB 2.0 support can store more data and transfer faster than a larger optical disc drive and can be read by other system like Playstation 3, etc.

Flash drives consists of small printed circuit board (pcb) carrying the circuit elements and a USB connector,  insulated electrically and protected inside a plastic, metal or rubberized case which can be carried in a pocket or on a key chain. The USB connector may be protected by a removable cap or by retracting into the body of the drive, although it is not likely to be damaged if unprotected. Most flash drives use a standard type-A USB connection allowing plugging into a port of a computer.

Flash drives get their power from the USB connection, and do not require a battery. But flash drives combined in a devices such as audio/video player may require battery to function.

Flash memory combines a number of older technologies with lower cost, low power consumption and small size made possible by recent advances in microprocessor technology. The memory storage was based on EPROM and EEPROM technology which has a limited capacity, slow in reading and writing, and requires a complex circuitry. The data must be completely erased before writing to it. Later the EEPROMs were developed and capable of erasing a certain region without affecting the other data.

Improve the memory structure involved copying the entire field into an off-chip buffer memory, erasing the field, modifying the data as required in the buffer, and re-writing it into the same field. With this, it requires a considerable computer support and EEPROM flash memory systems often have a built-in microprocessor system. Flash drives are more or less tiny version of this.

The development of high-speed serial data interfaces like USB made memory system with serial accessed storage possible. Simultaneous development of small, high-speed, low-power microprocessor system allowed this to be incorporated into very compact system.

Presently many audio player added extra software and power source to a standard flash memory control microprocessor so it can serve as a music playback decoder. Also the player can be used as a flash drive for storing files.