Computers have been categorized into generations based on their characteristics and the technologies used. The document discusses the first 5 generations of computers: 1) First generation used vacuum tubes from 1951-1959 and were very large and slow. 2) Second generation used transistors from 1959-1963 and were smaller and faster. 3) Third generation used integrated circuits from 1963-1975 and were smaller still with faster processing. 4) Fourth generation from 1975-today used VLSI chips and were small, fast, and user friendly. 5) Fifth generation computers of the future will use artificial intelligence.