In IGCSE Computer Science Unit 3 (Hardware), students learn how the physical components of a computer system work together to process data and run software. They study the role of key internal parts such as the CPU, memory (RAM and ROM), and storage devices, as well as input and output devices and how each is chosen for different purposes. The unit also introduces how data is represented inside a computer using binary, including numbers, text, images, and sound, and explores basic system performance factors like speed, capacity, and reliability. Overall, this unit builds a foundation for understanding what makes computers function and how hardware choices affect real-world use.