In networking a basic model was designed to enable complying software companies, rules to follow to ensure that similar and dissimilar operating systems could communicate. This is called the OSI model.
The OSI Model consists of seven layers. Each layer adds a header to the data being passed through it to prepare it for transfer. The combination of the data and these headers form what is known as a 'frame'. The header's job is to describe the frame's destination and what is to be done with it once it has arrived (what service has been requested) as well as other things.
At the receiving device the frame goes through the OSI model's seven layers in reverse order stripping away each layer's corresponding header then passing it up to the next layer until the data remains and the device knows what to do with it. Here are the seven layers:
 |
 |
 |
 |
 |
You can also check out the Protocols section in the works.