The document discusses the components that make up a modern computer. It explains that computers have evolved over time from being room-sized machines that could only perform basic calculations to now being small and powerful devices that are everywhere. It then lists and provides a brief description of the key internal components of a computer, including the central processing unit (CPU), random access memory (RAM), motherboard, power supply unit (PSU), hard drive, heat sink, fan, graphics card, sound card, CD drive, and USB ports.