Four generations of computers evolved beginning in the 1950s. Each generation reflected a shift toward smaller hardware but increased capabilities for controlling IT operations. The first commercial computer was developed by John Eckert and John W. Mauchly in 1951 and was known as the Univac 1. Over the next 25 years, mainframe computers were used to perform calculations in large businesses. Supercomputers were used in science and engineering, to design airplanes and nuclear reactors, and to predict global weather patterns. Minicomputers appeared in the early 1980s in small businesses, manufacturing plants, and factories. Computers today are divided into four categories based on their size, cost and processing capacity. These are supercomputers, mainframes, minicomputers and microcomputers, more commonly known as personal computers. Personal computers can be divided into desktop, network, laptop and handheld computers. In the 1970s, with the development of the Internet by the US Department of Defense, the information age was