What is the purpose of the power supply unit (PSU) in a computer?

The power supply unit (PSU) in a computer is essential for converting alternating current (AC) from the wall outlet into direct current (DC), which is the form of electricity required by the computer's internal components to operate properly. Most components in a computer, such as the motherboard, hard drives, and graphics cards, require DC voltage to function. The PSU not only performs this conversion but also distributes the appropriate voltages to different parts of the system, ensuring that each component receives the correct power needed for operation. This conversion and distribution are critical for the stability and performance of the entire computer system.