The application layer is the seventh and highest layer in the Open Systems Interconnection (OSI) model and provides a platform for applications to communicate over a network. The application layer defines the protocols used by applications to communicate with each other, as well as how they are represented.
The application layer is responsible for providing services to user processes or programs. These services include identifying communication partners, determining resource availability, and synchronizing communication. The application layer also provides an interface between the user and the network that allows applications to access network resources.
The most important protocols in the application layer are HTTP, FTP, SMTP, DNS, and Telnet. These protocols define how information is exchanged between diverse types of devices on a network.