Application Layer

The application layer is the highest layer of the OSI Model and is used by end-user software such as web browsers and email clients. It provides protocols that allow software to send and receive information and present meaningful data to users.

The layer is responsible for providing network services directly to user applications, enabling them to manage data, communications and collaboration over the network. This layer is crucial because it translates user requests into a format that can be understood and managed by the lower layers of the network.

Some examples of application layer protocols are HTTP Protocol, File Transfer Protocol, Post Office Protocol, Simple Mail Transfer Protocol and DNS.

This layer determines whether adequate resources exist for communication. It also manages communications between apps and directs data to the correct program. It is responsible for converting data into a format usable by applications and directing that data to the proper application window.

If multiple instances of an application exist, this layer ensures that data is delivered to the correct instance.