What are hubs? How are active hubs different from passive hubs?

A hub is a multi-port and unintelligent network device that simply transfers data from one port of the network to another. It is a hardware device used to connect several computers together using different ports.

Active hubs electrically amplify the signal as it passes from one connected device to another. They are often used like repeaters to extend the length of a network. In contrast, passive hubs allow the signal to pass from one computer to another without any alteration or amplification.