The document discusses the four main parts of a computer system: hardware, software, data, and users. It defines hardware as the physical components of a computer like keyboards and monitors. Software consists of organized instructions that control the computer and enable it to perform tasks. Data refers to raw facts that are stored and manipulated by the computer. Users are people who operate computers. The document then provides more details about hardware components like the CPU and memory, software types like operating systems and applications, and storage devices.