Networking is the practice of connecting computers and sending data between them. That sounds simple enough, but to understand how it works, you need to ask two fundamental questions:
How does the computer sending the data know where to send its data?
When the destination computer receives the data, how does it know what it just received?
A computer answers these questions by using a series of components, with each one responsible for a certain aspect of sending, receiving, and identifying data. The components are arranged in groups that form network layers, which stack on top of each other ...