A USB hard drive is a device that stores data retrievable by a computer on external hardware that is connected to the computer via a USB (Universal Serial Bus) port. This device is considered a convenient way to provide extra storage space to computers that have limited capacity on their internal drives, or for those users who want to backup some files or to easily transfer them to other computers.
The USB port offers a convenient way to connect an external USB hard drive to a computer system. Though the earlier versions of the protocol were not as fast, USB 2.0 has made substantial gains in speed, able to transfer data at 480 Megabits per second. USB 1.0 could only transfer at 1.5 Megabits per second. When large amounts of data are being transferred, which is usually the case with a USB hard drive, the speed can make a difference of not only minutes, but of hours. Now, an even faster version, USB 3.0, has arrived, and some external drives are able to take advantage of that technology as well.
Among the primary uses of these drives are the storage of large media files. This is especially true for those who have a lot of movies or music stored on their systems. Instead of using up the available space on their main hard drive, many opt to store such large files on an external USB hard drive. Further, they are often safer on such a system, as a computer crash will not affect those files, but could affect files on an internal hard drive.
This protection against crashes is why a USB drive may not only be used as a secondary storage device for larger files, but as a backup to the entire computer hard drive. Many USB hard drives come with software that makes backing up the entire contents of a hard drive easier to do. Still, the contents must be backed up regularly in order to provide the most comprehensive protection .
It is even possible to use a USB hard drive as a network storage device. If the hard drive is shared on a network, other users can access it, and store their own information there, thus keeping hard drives free across the network. In order for this to be truly effective, the hard drive must be connected whenever the network is being used. Otherwise users will not be able to store or retrieve information on the external USB hard drive.