Other software, such as word or paint shop pro, uses the operating system (OS) in order to perform tasks. This is known as software layering. The below diagram shows this layering.

An application asks the OS to save a file for it. The OS then talks to a hardware driver. A hardware driver is simply another piece of software which knows how to talk directly to the hard drive. The driver then saves the file. To read a file, the application would ask the OS for the file. The OS would ask the driver to read the file and the driver would read the file. The driver then passes the file back to the OS and then the OS passes the file back to the application.

This layering is used to reduce the amount of low level code (code which knows how to talk to hard ware) and to provide extra features such as security. If you have to use the OS to read a file, the OS could only allow you to read that file if you have the security privileges. The school network only allows you to read your own files and files on the public network drives.

The operating system is responsible for managing the computers resources. These include the storage devices, input and output devices, main memory and all software which is running on the computer.