Flash drives implement the USB mass storage device class so that most modern operating systems can read and write to them without installing device drivers. The flash drives present a simple block-structured logical unit to the host operating system, hiding the individual complex implementation details of the various underlying flash memory devices. The operating system can use any file system or block addressing scheme. Some computers can boot up from flash drives.
Yes you can but if you have a lot of files, a flash drive won't back it all up. If you only need to back up 32GB-64GB for example, you could back it up on the flash drive. However, anything bigger isn't sensible for flash drives; you're better off getting an external hard drive. Also, it's not a long-term storage option––it can corrupt easily or be lost.
_{You can get USB 3.0 speed in a compact and durable metal USB drive from Kingston for under $10. It sports a capless design with a sturdy keyring, perfect for travel or as a part of your everyday carry. The design can even be customized to add your logo or company name. Read speeds top 100 Mb/s, while write speeds are on the slow end. With a five-year warranty, a great design, and a value price, this small drive makes a perfect addition to your keyring.} 
^ 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.
Flash drives are often measured by the rate at which they transfer data. Transfer rates may be given in megabytes per second (MB/s), megabits per second (Mbit/s), or in optical drive multipliers such as "180X" (180 times 150 KiB/s).[19] File transfer rates vary considerably among devices. Second generation flash drives have claimed to read at up to 30 MB/s and write at about half that rate, which was about 20 times faster than the theoretical transfer rate achievable by the previous model, USB 1.1, which is limited to 12 Mbit/s (1.5 MB/s) with accounted overhead.[20] The effective transfer rate of a device is significantly affected by the data access pattern.[21]
“The Samsung BAR is incredibly small and easily portable, measuring just under 2-inches long,” our tester said. He added, “It's also extremely durable: waterproof, shockproof, as well as x-rays and magnets [proof].” The included key ring adds to its portability, according to our reviewer. On the flip side, he called the transfer speeds “decent but mostly unremarkable.” Our tester concluded, “Most of the BAR's problems are due to Samsung releasing a newer, cheaper model, the BAR Plus.”
USB flash drives use the USB mass storage device class standard, supported natively by modern operating systems such as Windows, Linux, macOS and other Unix-like systems, as well as many BIOS boot ROMs. USB drives with USB 2.0 support can store more data and transfer faster than much larger optical disc drives like CD-RW or DVD-RW drives and can be read by many other systems such as the Xbox One, PlayStation 4, DVD players, automobile entertainment systems, and in a number of handheld devices such as smartphones and tablet computers, though the electronically similar SD card is better suited for those devices.
_{USB flash drives are often used for storage, data back-up and transfer of computer files. Compared with floppy disks or CDs, they are smaller, faster, have significantly more capacity, and are more durable due to a lack of moving parts. Additionally, they are immune to electromagnetic interference (unlike floppy disks), and are unharmed by surface scratches (unlike CDs). Until about 2005, most desktop and laptop computers were supplied with floppy disk drives in addition to USB ports, but floppy disk drives became obsolete after widespread adoption of USB ports and the larger USB drive capacity compared to the 1.44 MB 3.5-inch floppy disk.}
Yes you can but if you have a lot of files, a flash drive won't back it all up. If you only need to back up 32GB-64GB for example, you could back it up on the flash drive. However, anything bigger isn't sensible for flash drives; you're better off getting an external hard drive. Also, it's not a long-term storage option––it can corrupt easily or be lost.
If you are taking your data to the extreme ends of the Earth and need to go a step above and beyond to keep it safe, the rugged Corsair Flash Survivor Stealth 64-bit is the drive for you. Constructed with aircraft-grade aluminum housing and outfitted with a molded shock damping collar, this drive is meant to survive anything you can throw at it. It can even be submerged in up to 200 meters of water because of the EPDM (ethylene propylene diene monomer rubber) waterproof seal. With speeds at around 85 MB/s, this isn’t the fastest drive around, but its ruggedness is unparalleled.
^{Most USB flash drives weigh less than 30 g (1 oz).[31] While some manufacturers are competing for the smallest size[32] with the biggest memory,[33] some manufacturers differentiate their products by using elaborate housings, which are often bulky and make the drive difficult to connect to the USB port. Because the USB port connectors on a computer housing are often closely spaced, plugging a flash drive into a USB port may block an adjacent port. Such devices may carry the USB logo only if sold with a separate extension cable. Such cables are USB-compatible but do not conform to the USB standard.[34][35]}

^ 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.

Artists have sold or given away USB flash drives, with the first instance believed to be in 2004 when the German punk band Wizo released the Stick EP, only as a USB drive. In addition to five high-bitrate MP3s, it also included a video, pictures, lyrics, and guitar tablature.[58] Subsequently, artists including Nine Inch Nails and Kylie Minogue[59] have released music and promotional material on USB flash drives. The first USB album to be released in the UK was Kiss Does... Rave, a compilation album released by the Kiss Network in April 2007.[60]

Many types of USB drive, sometimes referred to as a thumb drive, also have handy features like a key chain ring or a small LED flashlight. Some can even transmit your data wirelessly for the ultimate in digital convenience. And as with any fun accessory, there are plenty of novelty versions of flash drives designed to show your personality, display your sense of humor, or broadcast your team loyalty.