Before seeing the use of the USB hub, let us know what a USB hub is. Older computers have very low number of USB ports, say around two. It might be necessary to plug in more devices in to the computer than the number of the USB ports available. Hence we need a device or an external method by which we can increase the number of USB ports. Here is where the USB hub comes in to play.
A USB hub is nothing but, like an extension plug, for the USB port ion the computer. The USB hub consists of multiple ports. The USB hub is connected to the USB port of the computer and then the other end of the hub can be used to connect other external devices. The other end of the USB hub may contain more then one socket for increasing the number of devices that can be plugged in to the computer.
Thus the use of the USB hub is simple. It provides multiple sockets to connect multiple devices in to a single USB port. It is just like a multi pin socket.
USB hubs may be of USB 1.1 version or USB 2.0 version. The latter has the speed of around 480 megabits per second (mbps).The USB 1.1 has the speed of 12 megabits per second (mbps).The USB hubs of 2.0 version also supports 1.1 version devices , but it will not increase the speed of these 1.1 devices.