The operating system refers to the software that controls the functions of the computer itself. It provides a layer between the electronic functioning of the machine and all the other software tools and applications running on the computer. The operating system manages memory, processing power allocation and sharing, control of the electronic buses and all other machine-related aspects, providing a range of higher level services for use by all other software running on top of it. Most operating systems are proprietary, designed for specific hardware platform types and uses, although portable, open source operating systems are becoming increasingly popular.