# Application Layer | | An **Application Layer** is an abstraction layer that specifies the shared communication protocols and interface methods used by hosts in a communications network. An application layer abstraction is specified in both the Internet Protocol Suite (TCP/IP) and the OSI model. Although both models use the same term for their respective highest-level layer, the detailed definitions and purposes are different. | |-|-| | | wikipedia:: [Application layer](https://en.wikipedia.org/wiki/Application_layer) | - (Layer 7) - Protocol Data Unit: Data - [[Email]] - [[SMTP]] - [[Firewall]]s I think are usually at this layer? - WebSocket v - omnioutliner:///open?row=dPqvjEUgj\_2