data at the application layer is displayed correctly on
both systems. Also at this layer, the data is differentiated
and encoded based on the type of information it
contains, such as text files, video files, binary files, and so
on.
The application layer is the OSI layer that is closest to
the user and contains all the applications and protocols
that the users are interacting with, such as email, file
transfer, and video streaming. One application layer
protocol that is extensively used is Hypertext Transfer
Protocol (HTTP), which is at the heart of the World Wide
Web. Whenever a website is accessed on a web server,
the data between the client browser and the web server is
carried over HTTP.
The OSI model didn’t find much success when it was
initially developed, and it was not adopted by most
network equipment vendors at the time, but it is still
used for education purposes and to emphasize the
importance of separating data transmission in computer
networks into layers with specific functions.
The TCP/IP Model
A much more successful implementation of the layered
architecture to data transmission and device networking
is the TCP/IP (Transmission Control Protocol/Internet
Protocol) reference model, also referred to as the
Internet Protocol suite. Created around the same time as
the OSI model, the TCP/IP reference model was adopted
and implemented by most networking vendors back in
those days and has over time become the reference
model for the Internet.
The Internet Protocol suite and the main protocols that
make up the model, TCP and IP, started as a research
project by the U.S. Department of Defense through a
program called Defense Advanced Research Projects
Agency (DARPA) in the 1960s. It was the middle of the