A USB flash drive[note 1] is a data storage device that includes flash memory with an integrated USB interface. It is typically removable, rewritable and much smaller than an optical disc. Most weigh less than 30 g (1 oz). Since first appearing on the market in late 2000, as with virtually all other computer memory devices, storage capacities have risen while prices have dropped. As of March 2016, flash drives with anywhere from 8 to 256 GB were frequently sold, while 512 GB and 1 TB units were less frequent.[2][3] As of 2018, 2 TB flash drives were the largest available in terms of storage capacity.[4] Some allow up to 100,000 write/erase cycles, depending on the exact type of memory chip used, and are thought to last between 10 and 100 years under normal circumstances (shelf storage time[5]).
Some manufacturers, aiming at a "best of both worlds" solution, have produced card readers that approach the size and form of USB flash drives (e.g., Kingston MobileLite,[65] SanDisk MobileMate[66]) These readers are limited to a specific subset of memory card formats (such as SD, microSD, or Memory Stick), and often completely enclose the card, offering durability and portability approaching, if not quite equal to, that of a flash drive. Although the combined cost of a mini-reader and a memory card is usually slightly higher than a USB flash drive of comparable capacity, the reader + card solution offers additional flexibility of use, and virtually "unlimited" capacity. The ubiquity of SD cards is such that, circa 2011, due to economies of scale, their price is now less than an equivalent-capacity USB flash drive, even with the added cost of a USB SD card reader.
Most flash drives ship preformatted with the FAT32, or exFAT file systems. The ubiquity of the FAT32 file system allows the drive to be accessed on virtually any host device with USB support. Also, standard FAT maintenance utilities (e.g., ScanDisk) can be used to repair or retrieve corrupted data. However, because a flash drive appears as a USB-connected hard drive to the host system, the drive can be reformatted to any file system supported by the host operating system.
External flash drives use what's known as "solid-state" storage, which can store, back up, and retrieve data using only electronic circuits. Solid-state drives do not contain any moving mechanical parts, which enables them to access data quickly and easy. A typical flash drive allows up to 100,000 write/erase cycles before the integrity of the data starts to degrade. This translates to around a 10-year lifespan, depending on how much it is used.
Floppy disk hardware emulators exist which effectively utilize the internal connections and physical attributes of a floppy disk drive to utilize a device where a USB flash drive emulates the storage space of a floppy disk in a solid state form, and can be divided into a number of individual virtual floppy disk images using individual data channels.
^ Also known as a thumb drive, pen drive, gig stick, flash stick, jump drive, disk key, disk on key (after the original M-Systems DiskOnKey drive from 2000),[1] flash-drive, memory stick (not to be confused with the Sony Memory Stick), USB key, USB stick or USB memory. For an incomplete list of alternative names, see the list of redirects to this article.
M-Systems, an Israeli company, were granted a US patent on November 14, 2000, titled "Architecture for a [USB]-based Flash Disk", and crediting the invention to Amir Ban, Dov Moran and Oron Ogdan, all M-Systems employees at the time. The patent application was filed by M-Systems in April 1999.[6][1][7] Later in 1999, IBM filed an invention disclosure by one of its employees.[1] Flash drives were sold initially by Trek 2000 International, a company in Singapore, which began selling in early 2000. IBM became the first to sell USB flash drives in the United States in 2000.[1] The initial storage capacity of a flash drive was 8 MB.[7] Another version of the flash drive, described as a pen drive, was also developed. Pua Khein-Seng from Malaysia has been credited with this invention.[8] Patent disputes have arisen over the years, with competing companies including Singaporean company Trek Technology and Chinese company Netac Technology, attempting to enforce their patents.[9] Trek won a suit in Singapore,[10][11] but has lost battles in other countries.[12] Netac Technology has brought lawsuits against PNY Technologies,[13] Lenovo,[14] aigo,[15] Sony,[16][17][18] and Taiwan's Acer and Tai Guen Enterprise Co.[18]

There's a lot to choose from when it comes to buying a flash drive. The most important thing to consider is size. The whole point of a USB drive is to store lots of data in a small space, so think about what kinds of files you'll want to house on your flash drive. Movies and music take quite a bit of space, so if you're carrying your whole entertainment library with you, you'll want a big thumb drive – at least 16GB. Books and other text-based documents require relatively little storage space, so people like students and working professionals using Microsoft Office would be happy transferring Word documents or Excel files with as little as 1GB of space. On the other hand, if you are using photo or music editing software, you'll want a USB flash drive with lots of storage capacity to transfer graphic and music files.