Software that runs on a computer can be broadly divided into two types. There are two types, basic software and applied software. The basic software refers to the OS (operating system) such as Windows, mac OS, and Linux, and the application software includes Word, Excel, Power Point, etc. that run on the OS.
The basic software provides the "parts" necessary for the application software to operate, and the "resources" of the hardware. Has a role to manage. "Parts" are windows, menus and cursors required for users to operate application software (such as Word), and messages for opening and saving files. Without an OS, it would be necessary to create these functions every time to create application software, which would cost a lot of development. Therefore, the OS provides common functions used in application software. The "resources" of the hardware are the CPU, memory, etc., and the necessary amount is divided and given to the application software running on the OS. Also, since a computer can only perform one process at a time, it manages running application software and switches the processing timing at high speed to run multiple applications.