The application layer in the TCP/IP model is similar to the application, presentation, and session layers of the OSI model. The application layer is responsible for *making network requests or responding* to requests. This layer defines which internet services and applications any user can access. Protocols in the application layer determine how the data packets will interact with receiving devices. Some common protocols used on this layer are: - Hypertext transfer protocol (HTTP) - Simple mail transfer protocol (SMTP) - Secure shell (SSH) - File transfer protocol (FTP) - Domain name system (DNS)