Vint Cerf: Engineering a Network of Networks
Vinton "Vint" Cerf, born in 1943, is an American computer scientist widely regarded as one of the "Fathers of the Internet." In the early 1970s, computer networks were growing, but each was an isolated island. A machine on one network had no reliable way to communicate with a machine on another. Cerf, working with Bob Kahn, set out to solve this problem of internetworking.
Their answer was TCP/IP, the Transmission Control Protocol and the Internet Protocol. A protocol is simply an agreed-upon set of rules for how computers exchange information. TCP/IP is built on the idea of packet switching: a message is divided into small units called packets, each of which is routed across the network and reassembled at the destination. This design makes the network robust, because packets can flow around damaged or busy links and still be reconstructed correctly at the other end.
The two protocols divide the labor. IP is responsible for addressing and routing. Every device has an IP address, and routers use these addresses to forward each packet toward its destination, though IP by itself does not guarantee delivery. TCP sits on top and provides reliability: it numbers the packets, confirms that each one arrives, requests the re-sending of any that are lost, and reassembles them in the correct order. Together they let very different networks interconnect into a single "network of networks."
TCP/IP did not become universal overnight. It competed with other networking schemes until January 1, 1983, a transition sometimes called "flag day," when the ARPANET and the networks connected to it officially adopted TCP/IP as their standard. Standardizing on one protocol suite is what allowed the Internet to scale globally, because any network that spoke TCP/IP could join.
A crucial distinction often gets blurred in everyday language: the Internet is not the same thing as the World Wide Web. The Internet is the network of interconnected computers, built on TCP/IP. The Web, invented later, is one service that runs on top of the Internet, a system of linked pages accessed through browsers. For their foundational work, Cerf and Kahn received the 2004 Turing Award, computing's highest honor, and Cerf received the Presidential Medal of Freedom in 2005. He now serves as "Chief Internet Evangelist" at Google.
