Similar to its namesake in the OSI model, the application layer of the TCP/IP model acts as an interface between the applications themselves and the network stack, rather than the place the applications actually sit. Again, this is through the use of APIs and programming libraries. This layer performs the functionality of the application and the presentation layers of the OSI model, including the formatting, compression, and encryption of data.
There are a number of protocols in use on the application layer, and these can be divided into two areas:
- User protocols
- Support protocols
The user may have some involvement with the initial configuration of these, but then they are usually just left to do their own thing. We will discuss these protocols in more depth in upcoming sections.