History, structure, and function of the Internet.

The Internet stands at the forefront of telecommunications in medicine. This worldwide system of computers had its beginnings in networking projects in the United States and western Europe in the 1960s and 1970s. The precursor of the Internet was ARPANET, a long-distance telecommunication network funded by the Department of Defense that linked together computers throughout the United States. In the 1980s, ARPANET was superseded by NSFNET, a series of networks created by the National Science Foundation, which established the present-day structure of the Internet. The physical structure of the Internet resembles and is integrated with the telephone system. Long-distance data transport services are provided by large telecommunication companies, called network service providers (NSPs), through high-capacity, high-speed national and international fiber optic cables. These transport services are accessed through Internet service providers, ISPs. ISPs, the equivalent of regional Bell operating companies, provide the physical link to the NSPs for individuals and organizations. Telecommunications on the Internet are standardized by a set of communications protocols, the TCP/IP protocol suite, that describe routing of messages over the Internet, computer naming conventions, and commonly used Internet services such as e-mail. At present, the Internet consists of over 20 million computer worldwide and is continuing to grow at a rapid rate. Along with the growth of the Internet, higher speed access methods are offering a range of new services such as real-time video and voice communications. Medical education, teaching, and research, as well as clinical practice, will be affected in numerous different ways by these advances.