On this page, you will learn about the communication standards used on the Internet and how they work together.
Vint Cerf (born 1943) is an American Internet pioneer and is recognized as one of "the fathers of the Internet." Vint Cerf, along with Bob Kahn, co-developed TCP/IP, a framework for organizing the set of communication protocols used in the Internet and similar computer networks. Cerf has also served on the Board of Trustees of Gallaudet University, a university for the education of the deaf and hard-of-hearing. Cerf himself is hard of hearing and wears hearing aids.
There are billions of devices connected to the Internet and hundreds of different kinds of devices: laptops, tablets, phones, smart refrigerators, handheld credit card readers, and so on. How do they all know how to find and talk to each other? Protocols (communication standards) ensure that the variety of devices interact with each other smoothly.
Every device on the Internet has a unique Internet Protocol (IP) address (or more than one, if it's a router), like a postal or email address. The Internet Protocol specifies how a router handles a request for a different IP address. Each router knows the layout of its specific neighborhood of the Internet and knows which way to send each message to get it a little bit closer to where it's going. The fact that each router doesn't have to know the addresses of the complete Internet improves scalability.
When you stream data over the Internet, the stream is divided into packets that IP sends individually. This process is what makes the Internet a packet switching network.
The Internet is fairly reliable, but every once in a while a packet will be lost, and devices on the Internet need to tolerate these faults. One way to tolerate faults is not to care (if you lose one frame of video, it doesn't matter). Another way (called TCP for Transmission Control Protocol) is to keep sending packets until they are acknowledged as having been received correctly. For applications that use TCP, it's TCP that divides the data into packets. Since packets can travel by different paths, they may arrive out of order; and despite the redundancy of the Internet, it's possible some won't arrive at all. TCP guarantees reliable data transmission by keeping track of which packets have been received successfully, resending any that have been lost or damaged, and specifying the order for reassembling the data on the other end.
TCP/IP is a pair of protocols that provide two levels of abstraction:
Application layer: Browsers use HTTP (HyperText Transfer Protocol) to interpret HTML instructions for web page formatting. DNS (Domain Name System) converts user-friendly host names (like edc.org or berkeley.edu) into IP addresses. Your email application may use SMTP (Simple Mail Transfer Protocol) to send and IMAP (Internet Message Access Protocol) to read email.
Transport layer: TCP (Transmission Control Protocol) simulates a reliable, long-term connection between two computers by only displaying data once all packets have arrived. When speed is more important than accuracy, such as for real-time video streaming, people use UDP (User Datagram Protocol).
Internet layer: Every device on the Internet needs an IP address so other devices can find it. Routers use Internet layer protocols to detect and work around network congestion.
Network interface hardware: You may connect to the Internet with an Ethernet cable or perhaps a WiFi radio antenna inside the case of your computer. Either connects computers to a local network router which then connects to an Internet service provider (ISP). Cell phones use a longer-range cellular connection to a phone carrier.
There are a lot of protocols! The Internet was designed with several layers of abstraction that sort the protocols according to what part of the process they support. This hierarchy of abstractions manages the complexity of the Internet by hiding the details of lower levels of the system:
Before the Internet, there were several different network protocols that were secrets belonging to particular manufacturers. So if you had a particular brand of computer or router, it could talk only to other computers of the same brand.