These pages are in development and do not reflect the position of the GNU project.

What is an Operating System?

Think about a computer. What do you see? Maybe you see a monitor, a mouse, a keyboard and a computer case. All these things are physical. You can touch them with your hand. This means that they are material. All these things are called hardware. Other hardware components of a computer are the processor (the brain of the computer), different kinds of chips, and the motherboard for example. You will not be able to do many things by only using the hardware. You need software. You need an operating system with different programs that you can use.

Monitors, mice, keyboards and computer cases are all examples of hardware.

An operating system—this is the term we use—means a collection of programs that are sufficient to use the computer for a wide variety of jobs. A general purpose operating system, to be complete, ought to handle all the jobs that many users may want to do. For example, if you want to download a file from the Internet, you need to have an operating system which contains a program that can dowload files from the Internet. Software, programs and operating systems are not physical. They are just data. They are codes. You could compare them to feelings, musical compositions or literary works.

There are many different operating systems. You may have heard of Windows, DOS or Mac OS. These are all proprietary (non-free) operating systems. You are not allowed to use, change, share or study them freely. You do not have the freedom you deserve when you are using them. There are free operating systems, though. One of them is the GNU operating system. You may use GNU for whatever purpose you want to. You may change it, share it with others (including changed versions), and study how it works. These are all basic freedoms that every computer user in the world should have.

A kernel is the central part of an operating system. The kernel of GNU is HURD but it is not done yet so most people that use GNU use the Linux kernel.