Definition:

A network is collection of computers and mobile devices connected together via communication devices and transmission media, often wirelessly allowing computers to share resources (hardware,software, data and information).

Communication Device:

Hardware component that enables a computer to send (transmit) and receive data, intructions, and information to and from one or more computer.

Examples: 

1.     Modem - A device that enables a computer to communicate over analog networking media such connecting the Internet via telephone lines.  

2.     Wireless modem - modem that connects to the serial port but does not connect to telephone lines. It receives through the air.

3.     Wireless Access Point- a device on a network that connects wireless devices to that network.

4.     Router- a device that connects multiple networks together.

5.     Hub- The device that provides a common central connection point for nodes on network.

6.     Switch- a device used to connect multiple devices on a single (typically wired) network.

7.     Network Interface Cards(NIC)- an adapter card that connect a computer to a network.

8.     Wireless network interface card- an expansion cards through which a computer can connect to a network that provides wireless data transmission.

9.     Repeater- a device that enhance the weaken signal and repeat it at its original strength. 

Transmission Media:

 The materials or subtances capable of carrying one or more signal.

Types of transmission media:

•   Physical transmission media- send signals through cable,wire or tangible materials.

1.     Twisted pair cable

2.     Coaxial Cable

3.     Fiber Optic

•   Wireless transmission media- send signals through the air or space.

1.      Infrared

2.     Microwaves

3.     Cellular Radio

4.     Broadcast Radio

5.     Communication Satellite

6.     Bluetooth