What Is an OS?

A Government for your Computer

The Operating System (OS) is like the “central government” of the computer. It controls what happens on the computer, and provides basic services. Just like a government might provide water, roads, communications, and security, an OS provides video, keyboard, sound, printing, and network services.

In short, the OS does all the basic tasks so each program does not have to do everything.

For example, if you wish to build a house, what do you need?

  • Electricity
  • Water / Sewage
  • Gas
  • Garbage removal
  • Telephone service
  • Roads
  • Police protection
  • Fire protection
  • Military protection
  • Etc. ...

So, what will you do? Will you build your own road to your house? Will you get a generator and create your own electricity? Will you drill for natural gas, or perhaps buy large tanks of gas and keep them in your yard? Will you drill a well to get water, and take care of your own waste? Will you hire private police to protect you? And so on…

Of course, you will not do these things. That's what societies are for: they provide most or all of these basic services. This is important, because if we did not have these services, then it would be very expensive and terribly difficult and time-consuming just to carry out the basic tasks of everyday life.

In the same way, computer programs (also called "software" or "applications") do not have to take care of all the normal tasks that are necessary on a computer.

For example, let's say that I want to create a simple game. For that game, I need these services:

  • Video (to show my game)
  • Audio (to play sounds made in my game)
  • Keyboard (to control the game)
  • Mouse (also to control the game)
  • Fonts (to show text in my game)
  • Networks (to allow playing with other people)
  • Etc. ...

Now, if I had to create software for video and audio and keyboard and mouse and fonts and networking and all the other basic computer functions just for my little video game, I would have to spend years developing even just simple software.

Fortunately, the Operating System does all of that for me. I just have to know how to "call" for each service, and after that I don't have to do very much.

This is often described as the "layers" of a computer: (1) the hardware (machine) is the "bottom layer," the foundation; the next layer is (2) the Operating System, which works on the hardware layer; the next layer up (3) is made up of applications, the programs which work within the operating system. The last, or "top" layer (4) is you--the user--who works with the programs.

The OS is also like the government and the police, in that they make the laws and carry them out. The OS controls how programs behave, how much memory they can use, what rights they have, where they can and cannot go, and so on. Programs must follow these rules, or else the system breaks down.

In short: The OS makes it possible for programs (apps, software) to run on the computer.


An OS is not just one program; it is actually a collection of many, many smaller programs that work together. The companies that make an OS are always adding new programs, new features. Perhaps a data backup system, or new video routines, or a better touch interface, or voice control.

The OS will also get improvements in existing features. Maybe startup and shutdown times will be made faster, or new languages added; perhaps the appearance of icons and windows will be improved, or security will be made more reliable.

There are three kinds of upgradesAn "upgrade" means that you are getting something better than before.: a version upgradeFor example, XP, Vista, and Windows 7 are all full version upgrades., a "point" or "service pack" upgradeMac OS adds "point" upgrades, such as 10.5.1, 10.5.2, etc.; Windows will do "service pack" upgrades; each of these adds many fixes and improvements, and maintenance upgradesthese are smaller upgrades, and usually just fix specific problems or add small features.. Usually only full version upgrades cost money; the other upgrades are distributed free of charge.

What's a "Driver"? What is "OEM"?

You will probably hear about drivers from time to time. A driver is software which allows the Operating System to use a certain piece of hardware. For example, let's say that you have a computer, and you later buy a Blu-ray drive to use with it. Well, the Blu-ray drive is new, and so the computer won't know how to operate it. In order to use the Blu-ray drive, you must install the driver software, which teaches the OS how to use the new device.

Drivers are very important: if you don't have a driver, then you cannot use the hardware.

Even the hardware built into the computer must have driver software. When you buy a new computer, the drivers are pre-installed into the version of the OS which comes with the computer.

This special version of the OS is called an 'OEM"OEM" stands for "Original Equipment Manufacturer"' operating system. For example, when Sony makes a computer, they want all their computers to have the correct drivers for their machine. So they make a special version of Windows which has the drivers you need. This is why it is very important to keep the install discs that come with a new computer--they have the drivers you need!

This is a problem, however, when you upgrade a Windows computer to the next full-version OS. Let's say, for example, that you bought a Toshiba laptop a few years ago, and it came with Windows Vista. That copy of Vista was an OEM, meaning it had all the Toshiba drivers. You now decide that you wish to upgrade to Windows 7. So you go to the store and buy a copy of Windows 7, made by Microsoft. And that's the problem--the new OS you bought does not have the necessary drivers!

Often times, a computer company will make the drivers available for download from their web site, so you can get them before you upgrade, and then add them after you have installed the new OS. However, sometimes new drivers are not available, meaning that you cannot run your machine properly.

Before you upgrade to a non-OEM OS, check with the hardware maker to see if they have the drivers for your computer using the new OS. [Note: because Macintosh computers and the OS are made by the same company, this check is not necessary--the upgrade always works. However, if you buy extra hardware from a different company, they may not make drivers for the Mac OS, so make sure to check.]

Security & Maintenance

When you get a computer, I wish to remind you again: Keep the original install discs!!Really! I mean it! This is not just for the drivers, but in case you need to re-install the OS.

There are a few reasons why you might need to re-install. First, something might go wrong with the OS. The software might develop a malfunction, or there might be trouble with an upgrade. You might suffer a virus or other kind of malware"Malware" means software which "attacks" your computer. Viruses are one type of malware; others include "worms," "rootkits," and "trojan horses." Other malicious software includes "spyware" (which records and transmits your private info) and "adware" (which forces ads to jump up at you all the time). attack which cannot be fixed in any other way. If you don't have your original install discs, then you would have to buy Windows again, and you might have driver problems.

If you are using a Windows computer, it is important to have good security. While Windows 7 offers better security than XP, it is still necessary to use some kind of anti-virus softwareThis software is always running, in the background; it checks everything coming in to your computer for malware.. There are paid and free versions; the paid version are a bit better, but for many, the difference is very small. If you wish to have free anti-virus protection, you might want to try Avast.

Macintosh computers have no viruses. There are a few malware programs that could infect a Mac, but (a) they are rare, (b) require your permission to enter your computer, and © usually are found only on adult or pirate web sites. Best advice (for any computer): be cautious of any software you download from the Internet; the less respectful the web site, the greater the risk.

One note for Macs: good maintenance includes running the app titled "Disk UtilityThe Disk Utility app is free; look in the "Utilities" folder in your "Applications" folder." every once in a while. Under the "Disk First Aid" section, run the "Repair Disk Permissions" and "Verify/Repair Disk" processes every once in a while. If your main HDD shows problems under the "Verify Disk" test, then to repair it, you need to insert your OS install DVD-ROM, restart and boot up using the disc, and then run Disk Utility again.