This document provides a comprehensive overview of computer fundamentals, starting with the definition of a computer and its functions. It delves into the hardware components, including input and output devices, the central processing unit (CPU), primary and secondary memory (RAM, ROM, hard drives, optical disks, and flash disks). The document also explores software, differentiating between system and application software, and provides examples of each. It further explains units of measurement for computer storage and speed, and concludes with a classification of computers by size and power, including personal computers, workstations, minicomputers, mainframes, supercomputers, laptops, smartphones, and mobile devices. The document covers a wide range of topics providing a strong foundation in computer science.