Computers have five generations in which each generation of computer refer to technological development.
First Generation 1940-1956 computers used vacuum tubes as circuitry and magnetic drums for memory.
They took entire rooms and were very expensive.
Second Generation 1956-1963 used transistors and thus computers were smaller, faster, cheaper, more energy-efficient and more reliable than their first-generation computers.
Third Generation 1964-1971 used integrated circuits placed on silicon chips, called semiconductors, which increased the speed and efficiency of computers.
Fourth Generation 1971-Present used microprocessors, as thousands of integrated circuits were built onto a single silicon chip. Fifth Generation Present and Beyond based on artificial intelligence, are still in development.