This layer is responsible for the preparation of the data before it is presented.
This means the data is translated, encrypted or compressed so that the receiving device understands the data.

The presentation layer translates the data from previous layers. This data can be in different formats and so the presentation layer is the unifying layer that merges all formats into a standard format.

For example, the presentation layer may receive bits showing up as ones and zeros. It interprets this data and converts it into ASCII, this process is called translation.

It also does this the other way around. So, from ASCII to EBCDIC (eight-bit character encoding). Before the data is transmitted the presentation layer reduces the number of bits that represents the original data. This process is called data compression. Data compression reduces the amount of space that is used to store the original file. Because the data is compressed, the transmission can happen much faster. This is particularly helpful in video streaming for example.

To ensure the integrity of the data the date is encrypted before it is transmitted. Encryption enhances the security of sensitive data.

The data is encrypted on the sender’s site and is decrypted on the receiver’s side. The SSL protocol (Secure Sockets Layer) is used in the presentation layer for the encryption and decryption.


Exam Question

What operations does the presentation layer perform?

  • A. Encryption and Decryption
  • B. Translation
  • C. Compression
  • D. All of the above

The correct answer is: D

The presentation layer performs all of the above operations!

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