A computer network is a collection of two or more computers that are connected and share computer hardware / software resources. One of the earlist computer networks is the daisy chain network: where information is passed from computer (workstation) to computer in a chain. Modern day computer networks are far more sophisticated than daisy chains, and usually involve a primary computer - called a server - which is the hub of all network traffic. The Internet is one of the largest examples of a computer network, and is referred to as a 'network of networks'.
Before the late 1960's, computer networks were local: which meant that data did not travel across a large geographical area. However, in the late 1960's - inspired by the idea of Joseph Licklider's Global Network - ARPA provided funding to create an American wide-area computer network. This network - named ARPANET - connected nodes (host computers) located in states all across the United States of America, and eventually included nodes in Europe. ARPANET was one of the first examples of a computer network that was global, not local. ARPANET would inspire the creation of other wide area (global networks) networks, and, in the 1980's, some of these networks would interconnect to form the Internet.
Present day (2014), computer networks can be classified into the