The Internet is the world-wide network of interconnected computer networks (e.g., commercial, academic and government) that operates using a standardized set of communications protocols called TCP/IP (transmission control protocol/Internet protocol) or the Internet protocol suite.
An internet (spelled with a lower case i) is a network that is composed of a number of smaller computer networks. The Internet (spelled with an upper case I) is an internet that is vastly larger than any other internet and can be considered to be the ultimate internet; it connects thousands of networks and hundreds of millions of computers throughout the world.
In contrast to older communications systems, such as the traditional circuit-switched telephone networks (POTS), the Internet was purposely designed to be highly decentralized (both with regard to physical infrastructure and management) and independent of the underlying physical media. Any communications network that can carry two-way digital data can also carry Internet traffic; thus, Internet traffic flows through networks that use conventional copper wire, coaxial cable, optical fiber and radio waves.
One way in which the Internet accomplishes this is through the use of packet switching, which consists of dividing of messages into small units called packets before they are sent, transmitting each packet individually, and then reassembling them into the original message once all of them have arrived at the intended destination. This contrasts with circuit switching, in which a dedicated, but temporary, circuit is established for the duration of the transmission of each conversation. Thus, for example, if there is an overload or breakdown (e.g., a cut cable or a malfunctioning router) at some point along the initial route of packets, the system will automatically switch subsequent packets to other routes and retransmit any lost or damaged packets.
Also important in making possible the decentralized control of the Internet, along with all of the inherent benefits of such control, is the fact that TCP/IP, which defines packet switching and the various services offered by the Internet, consists entirely of free software instead of proprietary software (i.e., commercial software)1. That is, it is software that anyone can obtain at no cost (e.g., by downloading it from the Internet) and can use for any desired purpose, including studying, modifying and redistributing. Advocates of free software frequently emphasize that this is also a testament to the exceptionally high levels of innovation and quality that can be achieved with such software.
In network schematic diagrams, the Internet is often represented by a cloud symbol through which messages pass. This is a very appropriate symbol both because of the fact that packets, including the individual packets that comprise a single message, can travel by any of numerous different routes as determined by routers along the way and because the ordinary user does not know (nor need to know) the routes.
The Internet carries various types of services. Among the most popular of which are e-mail, the world wide web (WWW), file transfer protocol (FTP), newsgroups, file sharing and voice traffic2. These services can be accessed through numerous types of devices, the most familiar of which are personal computers, mobile phones and personal digital assistants (PDAs), which can connect to the Internet via dial-up, land line broadband (over coaxial cable, fiber optic or copper wires), terrestrial wireless and satellite links.
Each computer connected to the Internet, called a host, is independent both in the sense that its operator(s) can choose which Internet services to use and in the sense that they can make any desired information and services available to the global Internet community at virtually no cost and without notifying or receiving permission from any centralized authority. These operators can range all the way from major corporations and governments to individuals working in isolation in their bedrooms or basements.
This highly decentralized nature of the Internet and the lack of any centralized control is seemingly a prescription for anarchy. However, such anarchy by design has proven to be extremely efficient. It has resulted in a high degree of flexibility and robustness (i.e., the ability to operate effectively when localized equipment failure occurs or under other extreme conditions). It also facilitates the rapid introduction of new hardware and software technologies and has undoubtedly been a major factor in the swift growth in the use of the Internet and in the continued improvement in performance simultaneous with this growth.
The Internet has clearly been one of the most revolutionary inventions of the late twentieth century. It has already had profound effects on numerous areas of human activity, and, in the opinion of many experts, the Internet revolution has just begun. The variety and quality of services that it provides will continue to grow, and it will become an increasingly important factor in such diverse fields as education, communication, research, entertainment and medicine3. Moreover, its advance will likely make an increasingly large contribution to the growth rates of economies themselves4.
The origins of the Internet can be traced back to the 1950s, when communications researchers saw the great potential of interconnecting the widely divergent types of computers and communications networks that were then in use. This led to research into such areas as decentralized networks, queuing theory and packet switching, all of which were fundamental to the development of the Internet in its present form.
A major milestone was the creation of ARPANET in 1969 at the University of California at Los Angeles (UCLA) by the U.S. Defense Advanced Research Project Agency (ARPA). ARPANET was the world's first packet switching network and the precursor to the Internet. Subsequent milestones included the National Science Foundation's (NSF) construction in 1986 of a university network backbone, the NSFNet, and the opening of that network to commercial interests in 1995.
Still in its infancy, the Internet has already evolved into something far beyond what its developers could have imagined. Although it faces major challenges, particularly in the form of attempts by governments and corporations to censor and control it (with a consequent risk of stifling innovation), so far, the system as a whole has resisted these efforts exceedingly well.
2Voice traffic on the Internet is provided by a service called voice over Internet protocol (VoIP), whose use is growing rapidly and which is expected to increasingly replace conventional circuit switched telephone service. It is interesting to note that the Internet began life by operating on an infrastructure that had been designed almost exclusively for voice communications but that the situation is in the process of becoming reversed with the global communications infrastructure becoming primarily designed for the Internet, which carries voice traffic as just one of its many services.
3Among the ways in which the Internet is expected to, or is already starting to, affect the medical field are (1) making medical information, including costly medical libraries, less expensive and more widely available by providing them online, (2) allowing the real time examination of patients in remote areas through the use of video conferencing that incorporates the transmission of high resolution images, electrocardiograms and other medical data and (3) allowing busy doctors and hospitals to send X-ray images to specialized diagnostic centers in other time zones for overnight and low cost analysis.
4This is not meant to imply that everything about the Internet is good -- it certainly is not. It has frequently been used for unethical or nefarious purposes, just as has been the case with the telegraph and telephone before it, and just as has been true for virtually all technologies.
Created December 30, 2005.