The Internet is a global network of linked computer networks that communicate with one another and with devices using the Internet protocol suite. . Private, public, academic, business, and government networks with local to global reach are connected using a variety of electronic, wireless, and optical networking technologies. A few of the various information sources and services accessible on the Internet include the World Wide Web (WWW), which is composed of interconnected hypertext documents and applications, as well as electronic mail, phone service, and file sharing.
The development of packet switching and the time-sharing capabilities made possible by research commissioned by the US Department of Defense in the 1960s are the foundations of the Internet. The largest precursor network, ARPANET, initially served as a backbone for tying together local academic and military networks in the 1970s. In the 1980s, private financing for further commercial extensions as well as the funding of the National Science Foundation Network as a new backbone contributed to the development of new networking technologies and the joining of other networks. As successive generations of institutional, personal, and mobile computers were linked to the network in the early 1990s, this marked the start of the transition to the contemporary Internet. This expansion was sustained exponentially. Despite the fact that academia made extensive use of the Internet in the 1980s, commercialization integrated its products and services into almost every facet of contemporary life.