It is the set of physical parts of a computer system, i.e. the parts and hardware of a computer such as a monitor, keyboard, data storage media (such as a hard disk), the system unit (graphic cards, sound cards, memory, motherboard, other chips), etc. That is, all material things that can be touched. In contrast, software and data are not included in the description of computer hardware. Software exists as ideas, applications, concepts, and symbols, but it is not physical. Software is a set of instructions that are stored and operated by hardware. Software is a set of machine-readable instructions that direct a computer processor to perform specific operations. The combination of software and hardware (parts) of a computer constitutes a usable computer system.