Computer work through an interaction of hardware and software. Hardware refers to the parts of a computer that you can see and touch, including the case and everything inside it. the most important piece of hardware is a tiny rectangular chip inside your computer called the central processing unit (CPU) , or microprocessor. It's the "brain" of your computer-the past that translates instruction and performs calculations. Hardware items such as your monitor, keyboard, mouse, printer, and other items are often called hardware devices, or devices