The presentation layer of an OSI (Open Systems Interconnection) model is the layer that is responsible for ensuring that the communications that are passing through the network are in proper formatting for the end user. An example of proper formatting can be Postcript, ASCII, and binary. This layer also deals with compatibility with host operating systems as well as encapsulation of data into “envelopes” for the transmission of the messages. This layer is the 6th layer within a 7 layer OSI model.
To make this layer purpose and functionality easy to understand I will give you a scenario of its use. Imagine you are looking for a video online. You open your web browser. This layer this layer will manage the HTTP (Hypertext Transfer Protocol). It will transfer you to your appointed homepage when you open your browser.
Once you type in your search criteria it will then translate that and you will be redirected to the search results. This will continue until you find the video you have been searching for.
When you download the video you have been searching for or click on the file to watch the video the presentation layer deciphers the file type by reading the MIME (Multi-Purpose Internet Mail Extensions) header which indicates which type of file it is so the proper utility player can be used to present the file to the end user. This will allow for the video file that you have been looking for to properly be displayed and watch within your browser.
In summary this layer allows for the encryption/decryption of files, character/string conversion, data compression, and graphic handling. It’s main function is to translate data between the application layer and the network format. This layer ensures that different formats from different sources can communicate and be displayed to the end user in a usable format.