The Sixth layer of the OSI Model- The Presentation layer
We can find the purpose of the Presentation layer from its name. It present the data to the Application layer and responsible for the data translation and for the code formatting. The presentation layer defines how the system provides the files and services in a uniform way to application.
When the data is transmitted between different types of computer system from the source point to the destination point, the presentation layer manages the way in which the data is represented and encoded .The presentation layer usually a part of the operating system, that convert the incoming and the outgoing data from the one presentation format to the another presentation format. It some time called the Syntax layer.
The Presentation layer is a translator and provides coding and the conversion function. By providing the translation services the presentation layer ensure that the data transfer from the Application layer of one system can be read by the application layer of the another system. This layer associated with the task like-data compression and decompression, encryption and decryption etc.
Responsibilities of the Presentation layer-
1. The Presentation layer at the sender point changes the information dependent format into a common format and the Presentation layer at the receiving point changes the common format into the receiver dependent format.
2. This layer provides the encryption and decryption. Encryption means that the sender transforms the original information to other form and sends the message over the network.
And the Decryption process to transform the message back into its original form.
3. This layer provides the data compression that reduces the number of the bits to be transmitted .Data compression is important in the transmission of multimedia such as-audio and video.
The protocols use in the Presentation layer are –JPEG(Joint Photographic Expert Group),TIFF(Togged Image File Format),PICT(A Picture format),MPEG(Moving Picture Expert Group),MIDI(Musical Instrument Digital) etc.
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