WHAT IS HUB?

Hub is a device that are used for same Collision domain.It is basically a center point in the LAN. It is also used in network as Repeater So It Repeat Electrical Signal that comes in one port out all other port. HUB are layer one device in OSI model  and not uses Ethernet frame or addressing. That's why they can't decide which port a signal should be sent . Hub send data through broadcast. Hubs are currently not used because It create unnecessary traffic in the network. And this work in half duplex mode and can easily captured by Network Sniffing.