Application Layer
The application layer is the top layer of the OSI model. Many people consider the top three layers of the OSI model to be application related.
This layer is where the software interacts with the user. Examples of this are web browsers and email clients.
Technically the software itself is not part of the application layer. It’s the networking functions of the operating system that the applications use. For example, APIs.
True examples of this are HTTP (used for web browsing) and SMTP (used for email).