The Network Layer is Layer 3 (of seven) in the OSI model of networking. The Network Layer responds to service requests from the Transport Layer and issues service requests to the Data Link Layer.
In essence, the Network Layer is responsible for end-to-end (source to destination) packet delivery including any routing through intermediate hosts, whereas the link layer is responsible for node-to-node (hop-to-hop) frame delivery on the same link.
The Network Layer provides the functional and procedural means of transferring variable length data sequences from a source to a destination via one or more networks while maintaining the quality of service, and error control functions.
The Network Layer deals with transmitting information all the way from its source to its destination – transmitting from anywhere, to anywhere.