Internet is conceptualized as five separate, independent and modular layers: the physical layer, the data link layer, the network layer, the transportation layer.The application layer  and TCP/IP  sits on top. Consists of a set of protocols (such as HTTP, FTP, SMTP, and DNS) that enable  people to share information, swap messages, transfer files, or resolve domain names into their corresponding IP addresses. TCP (Transmission Control Protocol) ensures that data packets sent through the IP layer are properly delivered, in the appropriate order. The IP layer governs the delivery of data packets, the transport layer is concerned with data’s fragmentation and reassembly.