Basic Hardware Components

All networks are made up of basic hardware building blocks to interconnect network nodes, such as
1.    Network Interface Cards (NICs),
2.    Bridges,
3.    Hubs,
4.    Switches, and
5.    Routers.

A network card, network adapter or NIC (network interface card) is a piece of computer hardware designed to allow computers to communicate over a computer network.
A repeater is an electronic device that receives a signal and retransmits it at a higher level or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances without degradation.

Hubs
A hub contains multiple ports. When a packet arrives at one port, it is copied to all the ports of the hub. When the packets are copied, the destination address in the frame does not change to a broadcast address. It does this in a rudimentary way; it simply copies the data to all of the Nodes connected to the hub.

Bridges
A network bridge connects multiple network segments at the data link layer (layer 2) of the OSI model.

Switches
Switches are a marketing term that encompasses routers and bridges, as well as devices that may distribute traffic on load or by application content (e.g., a Web URL identifier).

Routers
Routers are the networking device that forward data packets along networks by using headers and forwarding tables to determine the best path to forward the packets that have been integrated with routers to allow multiple home computers to access the Internet.