Application Layer in OSI Model in Computer Networks

In this tutorial, we are going to learn about application layer in OSI model.

In the OSI model, the application layer is the layer closest to the end user, which implies both the application layer and the end user can interact directly with the software application. Both client and server programs make up the application layer.

Functions of Application Layer in OSI Model :

Users can forward numerous emails using the Application Layer, which also serves as a storage facility.

This layer allows users to access, retrieve, and manage files on a remote computer.

It also allows users to connect to the system as if it were a remote host.

Users can access global data on a variety of services through this layer.

E-mail, file transfer, results distribution, directory services, network resources, and other services are provided by this layer.

It generally establishes protocols that enable software to send and receive data and present it to users in a meaningful manner.

It deals with a variety of topics, including network transparency and resource allocation.

Users and application processes can access network resources through this layer, which basically serves as a portal.

Services of Application Layer in OSI Model:

Network virtual terminal : 

A user can log on to a remote host using an application layer. The application accomplishes this by emulating a terminal on the remote machine in software. The user’s computer interacts with the software terminal, which in turn interacts with the host. The user is allowed to log on as the remote host believes it is connecting with one of its own terminals.


A user can use an application to access files on a distant computer, retrieve files from that computer, and also manage data on that machine. In terms of file structure, file attributes, and the types of operations done on the files and their attributes, FTAM specifies a hierarchical virtual file.

Addressing :

There is a requirement for addressing in order to obtain communication between client and server. When a client sends a request to the server, it includes the server’s address as well as the client’s own. The client request contains the destination address. For example, client address, which is included in the server response. DNS is necessary to accomplish this type of address.

Others : 

Email forwarding and storage are provided by an application layer. A distributed database in an application offers access to global information about multiple objects and services. It verifies if the message was sent by the sender or received by the receiver, or both.