The document provides an introduction to understanding the computer system. It discusses the major hardware components of a computer system including the system unit, motherboard, CPU, primary storage, expansion bus, adapters, power supply unit, hard disk drive, optical drive, and digital versatile disc. It also covers input devices like the keyboard and pointing devices, output devices like the computer display monitor and printer, ports, cables, and system and application software. The goal is to familiarize readers with the basic components and functions of a computer system.