A USB flash drive -- also known as a USB stick, USB thumb drive or pen drive -- is a plug-and-play portable storage device that uses flash memory and is lightweight enough to attach to a keychain. A USB flash drive can be used in place of a compact disc. When a user plugs the flash memory device into the USB port, the computer's operating system (OS) recognizes the device as a removable drive and assigns it a drive letter.
A USB flash drive can store important files and data backups, carry favorite settings or applications, run diagnostics to troubleshoot computer problems or launch an OS from a bootable USB. The drives support Microsoft Windows, Linux, MacOS, different flavors of Linux and many BIOS boot ROMs.
The first USB flash drive came on the market in 2000 with a storage capacity of 8 megabytes (MB). Drives now come in capacities ranging between 8 gigabytes (GB) and 1 terabyte (TB), depending on manufacturer, and future capacity levels are expected to reach 2 TB.
The memory within most USB flash drives is multi-level cell (MLC), which is good for 3,000 to 5,000 program-erase cycles. However, some drives are designed with single-level cell (SLC) memory that supports approximately 100,000 writes.
How a USB flash drive is used also affects its life expectancy. The more users delete and write new data on the device, the more likely it will degrade.