The document describes the main internal and external parts of a computer. Internally, it discusses the microprocessor/CPU, motherboard, RAM, HDD, optical drives, and graphics card. Externally, it mentions the display, microphone, printer, keyboard, scanner, speakers, mouse, and cabinet. The motherboard synchronizes all internal parts, RAM temporarily stores data, the HDD stores large amounts of data permanently, and the graphics card processes graphics and sends signals to the display.