But applications software cannot communicate directly with the hardware , so the operating system serves as middle software between the applications software and the hardware. An operating system is a set of programs that lies between applications software and the computer hardware, it is the basic software that controls access to all
other software and hardware resources. The picture below gives a conceptual picture of operating system software as a middleman between the hardware and the applications
software.
Systems software includes the operating system. and it also includes programming language translators and a many service programs.