What is the role of Application layer in the OSI model

Access to network services is provided by the application layer. It interacts with software applications by identifying resources, determining availability, and distributing information. Moreover, it synchronizes peer applications that run on different systems.
Telnet, File Transfer Protocol (FTP), SMTP (Simple Mail Transfer Protocol), SNMP (Simple Network Management Protocol), NFS (Network File System), and BGP (Border Gateway Protocol) are examples of application layer specifications.

File sharing, email, etc., are application layer services. Some application services (such as networked printers) periodically advertise their availability to other devices on the network. However, some services register themselves in a centralized directory (for example, Microsoft Active Directory) that can be queried by others. It is often misunderstood that end-user applications (such as Microsoft Word) reside at the application layer. Application layer services are consumed by end-user applications. Email is an application layer service that lives at the application layer, whereas Microsoft Outlook (an example of an email client) lives at the end-user level. The application layer also advertises available services.