The internet trasmits data from on computer(called a host) to another. If the receiving computer is on a network to which the first computer is directly connected, it can send the messege directly. If the receiving and sending computers are not directly connected to the same network,the sending computer relays the messege to another computer that can forward it. The messege might be sent through a router to reach the forwarding computer. The forwarding host,which presumably is attached to atleast one other network, delivers the the messege directly if it can or passest it to another forwarding host. A messege can pass through a dozen or more forwarders on its way from one part of the internet to another.
The various networks that are linked to form the internet work much the same way they pass data around in chunks called packets, each of which carries the addresses of its sender and its receivers. The set of conventions used to pass packets from one host to another is known as the internet protocol(IP).Many other protocol are used in connection with ip. The best known is the transmission control protocol (TCP)