Application Layer (Layer 7) At the very top of the OSI Reference
Model stack of layers, we find layer 7, the application layer.
Continuing the trend that we saw in layers 5 and 6, this one too
is named very appropriately: the application layer is the one
that is used by network applications. These programs are what
actually implement the functions performed by users to
accomplish various tasks over the network. It's important to
understand that what the OSI model calls an application is not
exactly the same as what we normally think of as an application.
In the OSI model, the application layer provides services for
user applications to employ. For example, when you use your Web
browser, that actual software is an application running on your
PC. It doesn't really reside at the application layer. Rather,
it makes use of the services offered by a protocol that operates
at the application layer, which is called the Hypertext Transfer
Protocol (HTTP). The distinction between the browser and HTTP is
subtle, but imp