Definition:

The Internet is the worldwide system of interconnected computer networks that exchange data through the TCP/IP protocol suite. It connects devices, home networks, businesses, universities, public administrations, data centers and telecommunications providers without relying on a single central network.

The Internet is not a company, a single cloud or one particular service. It is a distributed infrastructure of networks whose participants use shared technical protocols to identify destinations, divide information into packets, transport it and reconstruct it on arrival.

Its name comes from “internetwork”, a term used to describe the interconnection of networks. Internet is not an acronym and does not officially stand for “Interconnected Networks”, even though that phrase roughly describes its function.

How the Internet works

When a device connects, it normally does so through an Internet service provider. Data is divided into packets that may follow different routes. Routers forward them between networks using IP addresses until they reach the destination system.

Several layers and services work together to make a connection usable:

Access: Fiber, cable, mobile networks, Wi-Fi or satellite connect the device to a provider.
IP addressing: Identifies interfaces and helps determine which network should receive each packet next.
Routing: Routers and routing protocols select paths between autonomous networks.
Domain Name System: Translates readable names, such as a web domain, into addresses used by computers.
Application protocols: Define how services such as the Web, email, file transfer and real-time communications operate.

The Internet and the World Wide Web

The Internet and the World Wide Web are not synonyms. The Internet is the communication infrastructure; the Web is one of the services that operates on it. The Web organizes linked documents and applications accessed through browsers, URLs and protocols such as HTTP or HTTPS.

Many services other than the Web also use the Internet:

Email: Exchanges messages and files between servers and accounts.
Messaging and calls: Supports real-time text, voice and video conversations.
File transfer and storage: Sends, synchronizes and stores files on remote systems.
Streaming: Delivers continuous audio, video and live broadcasts.
Games and applications: Connect users to interactive services and remote systems.
Connected systems: Sensors and Internet of Things devices that exchange information.

Origin and development of the Internet

The Internet has roots in packet-switching research conducted during the 1960s. In 1969, ARPANET connected its first nodes at United States research centers. The project was funded by the Department of Defense’s ARPA agency, but it also sought to share computing resources and improve communication among researchers.

During the 1970s, Vint Cerf and Bob Kahn developed the foundations of TCP/IP to connect different networks. ARPANET’s adoption of these protocols on January 1, 1983 is considered a milestone in the formation of the Internet. Academic networks such as NSFNET later expanded connectivity and supported its growth.

In 1989, Tim Berners-Lee proposed the World Wide Web at CERN and subsequently developed components including HTML, HTTP and the first browser-server system. Commercial access, broadband, mobile networks and cloud services eventually extended the Internet far beyond its academic origins.

What the Internet is used for

The Internet enables people and systems to exchange information over distance. Its uses depend on the service and access conditions, but they cover personal, professional and public activities:

Communication: Email, messaging, video calls, forums and social networks.
Information and publishing: Access to and distribution of news, documents, data and multimedia.
Education and research: Remote learning, libraries, scientific collaboration and access to resources.
Work and collaboration: Remote work, shared applications, project management and remote access.
Commerce and services: Shopping, banking, public procedures, bookings and customer support.
Entertainment: Video, music, games, broadcasts and digital communities.

Infrastructure and access methods

Global connectivity depends on a physical and logical infrastructure of fiber-optic networks, submarine cables, antennas, satellites, routers, exchange points, data centers and naming systems. Although many interfaces are described as “the cloud”, data travels through and is stored on equipment in specific locations.

A connection may be fixed or mobile and provide different levels of speed, latency, stability and data allowance. An intranet, by contrast, is a network restricted to an organization or community. It may use the same technologies, but it is not itself the global public network.

Limitations and risks

The Internet’s reach does not remove inequality. Differences remain in coverage, cost, devices, accessibility and digital skills, collectively known as the digital divide. Blocking, censorship, outages and dependencies on providers or critical infrastructure also affect access.

Global connectivity supports collaboration and access to information, but it also exposes users and systems to fraud, malware, impersonation, surveillance, privacy loss and false content. The Internet is therefore an open and useful infrastructure, but not automatically free, secure or neutral.