Computers are powerful productivity tools for business and personal use. Recently the form factor of computers has shifted from bulky desktops to more mobile devices like laptops, tablets and even phones. Desktop computers are still in use, however. A typical desktop device includes the CPU, or central processing unit. This is the brain of the computer to which all the peripherals are attached. Chief among these are the monitor and the keyboard, with an optional printer for hardcopy output and a universal power supply (UPS) to protect against power failures. Desktop computers run powerful menu-driven operating systems like Windows and macOS.