Computer hardware includes the physical parts of a computer, such as a case, central processing unit (CPU), monitor, mouse, keyboard, computer data storage, graphics card, sound card, speakers, and motherboard. By contrast, the software is the set of instructions that can be stored and run by hardware. Hardware is so-termed because it is “hard” or rigid with respect to changes, whereas software is “soft” because it is easy to change. Hardware is typically directed by the software to execute any command or instruction. A combination of hardware and software forms a usable computing system, although other systems exist with only hardware. A peripheral or peripheral device is an auxiliary device used to put information into and get information out of the computer.