A network is a group of interconnected systems that share services and interact through a communications link. So, for a network to exist, there must be two or more individual systems with something to share, like data. And, in order for these individual systems to share, they must be connected through some type of physical pathway or transmission medium. Now, if data is being sent over the transmission medium, all these individual systems must follow a set of common communication rules in order for the data to arrive at its intended destination or for the systems to properly understand each other in order to receive the data. These rules that govern how the systems communicate are known as protocols.
Now, just having a transmission pathway should not suggest that communication is automatic, because in order for two systems to communicate, they must be able to understand each other. Data cannot simply be exchanged. The data that is received must be understood. So, the true goal of computer networking is not just to exchange data, but also to be able to understand and use the data that has been received.
So, to quickly summarize a network, there are four things that must be present:
- two or more indivdual systems
- something to share (ex: data)
- a physical pathway or transmission medium
- rules of communication or protocols