The document summarizes the four generations of computers from 1945 to present day. The first generation used vacuum tubes and were large and unreliable. The second generation used transistors, which were smaller and more durable. The third generation used integrated circuits, making computers even smaller. The fourth generation used VLSI technology to put millions of transistors on a single chip, reducing costs and power consumption. Today's computers are classified as fourth generation and are faster, more powerful, and affordable.