The Application Layer

The OSI definition

In the Open Systems Interconnection (OSI) communications model, the application layer provides services for an application program to ensure that effective communication with another application program in a network is possible. The application layer is NOT the application itself that is doing the communication. It is a service layer that provides these services:

It may be convenient to think of the application layer as the high-level set-up services for the application program or an interactive user.

Internet applications

 Concerning the Internet application layer, it consists on a set of protocols providing different services. Among these, the most popular are: