The Network Layer or the Internet Layer, is one of the five layers in the TCP/IP 5 Layer Model, it represents the connections between different networks.
The network layer is also sometimes called the Internet layer. It’s this layer that allows different networks to communicate with each other through devices known as routers. A collection of networks connected together through routers is an internetwork, the most famous of these being the Internet.
While the data link layer is responsible for getting data across a single link, the network layer is responsible for getting data delivered across a collection of networks. Think of when a device on your home network connects with a server on the Internet. It’s the network layer that helps gets the data between these two locations. The most common protocol used at this layer is known as IP or Internet Protocol. IP is the heart of the Internet and most small networks around the world. Network software is usually divided into client and server categories, with the client application initiating a request for data and the server software answering the request across the network. A single node may be running multiple client or server applications. So, you might run an email program and a web browser, both client applications, on your PC at the same time, and your email and web server might both run on the same server.