What is a presentation layer?

The presentation layer changes the data from an application layer into the device native internal mathematical structure and encodes communicated information into a displayable output format.

It executes the code changes, document compressions, security encryption, etc. It also defines the data as per the software/hardware environment of the hub. For instance, demonstrating UNIX structured data in windows.

The link between the presentation layer and the application and session layer has been shown in the diagram below −

It is concerned with the syntax of data.


The procedure in two frameworks are generally to exchange the data in the form of character strings, numbers etc. The data must be exchanged into a bitstream before being transmitted.


To carry any sensitive data, the presentation layer encrypts the data at the sender's end and decrypts at the receiver's end.


Compression means the reduction of bits. It is required in the case of multiline text, audio and video.

Function of presentation layer

The functions of presentation layer are explained below −

  • Data Compression: It decreases the various bits to be sent by shrinking the data.

  • Data Conversion: It layouts the data on several hubs according to the software/hardware environment.

  • Code Conversion: The form and syntax (language) of the two connecting frameworks can be different. One framework uses the American Standard Code for Information Interchange (ASCII) code to document transfer, and the other facilitates the Extended Binary Coded Decimal Interchange Code (EBCDIC) developed by the Computer hardware company IBM. It offers the "translation" from ASCII to EBCDIC and vice versa.

  • Data Encryption: It encodes information in a particular format so that each user or application cannot understand it.

  • All the receiver end performs the decomposition, decoding and decryption.