What is hub ? What are its types ?

A hub is networking device having multiple ports that are used for connecting multiple computers or segments of a LAN together. Hubs are of two types:

1. Active hubs — They electrically amplify the signal as it moves from one connected device to another. Active concentrators are used like repeaters to extend the length of a network.
2. Passive hubs — They allow the signal to pass from one computer to another without any change.