Definition :  a network is a set of devices (often  referred to as nodes) connected by communication link.

A node can be a :

  • Copmuter


  • Printer


  • or any device capable of sending and/or reciving data generated by nodes on the network.

Connection of two nodes
communication links :
- Twiated pair
- Coaxial cable
- Optical fiber
- Free space (through air)