Answer: Computers typically recognize USB flash drives (often called 'keychain drives') the same as other hard drives or removable media. This means you can drag and drop files to a USB drive, just like you can with your internal hard disk. If you use a Mac, the USB drive should show up on your desktop a few seconds after you connect it to your computer. If you use Windows XP or later, the drive should show up in 'My Computer,' along with your hard drives, optical drives, and any other storage media. On both Macs and PCs, you can open USB hard drives by simply clicking drive's icon.
The heaviest use a flash drive is likely to see is when it is used as a ReadyBoost drive. This is when Windows is allowed to use flash as a buffer for a hard drive. I have two 8 GB drives serving that function and they each see daily use of around 4 GB per day.
If you have Windows Me or earlier, you should be able to use most USB drives, though some may be incompatible with your computer. Certain drives only support Windows XP or later. If your computer does not recognize a USB flash drive, find out who the manufacturer of the drive is. Then use your Web browser to visit the company's website and see if you can download drivers for your operating system. Installing the correct drivers from the manufacturer may allow your computer to use the USB drive even if your operating system doesn't natively support it.