This document describes the major hardware and software components that make up a computer system. It explains that a computer contains a central processing unit (CPU) and memory chips housed within a computer case. Other key internal components include video cards, hard disks, and random access memory (RAM). External components that interface with the computer are also outlined, such as keyboards, mice, monitors, printers, and networking cards. The document concludes by discussing operating systems like DOS and Windows, which connect hardware and allow users to run application programs.