In short, Linux is an operating system. Like Microsoft's Windows and Apple's Macintosh and iMac, but like none ever created. It is different in that while Microsoft and Apple sell their products for money and keep it's innards a close-kept corporate secret, Linux is developed in the open for anyone to see by thousands of talented people the world over and given away for free. Why, you ask, would anyone want to do that? Think about it. Why do you hold the door for the stranger when entering the post office? Why do you help a friend put a new roof on their house? You know your only payment is in the sense of well being you get in return for an act of kindness. Linux was and still is being created in the exact same spirit. It's license, the General Public License, guarantees that it can never be owned by anyone but will always be free. Like the air we breathe, nobody 'owns' it but everyone is responsible for keeping it clean and free of pollutants.
But now let's look at how Microsoft does business. It is a fact that Microsoft is the most common software used on computers today. Every new computer sold comes conveniently loaded with the latest version of Windows. Microsoft likes that very much. They go to great lengths to keep it that way. They want to make sure you continue to use their products whether you choose to or not. They want you to think 'why would I NOT want to use Windows?' so you will continue to buy their products and only their products. But here is where things become apparent. When you run their software, you agree to what's called the End User License Agreement (EULA). You are the 'End User'. Have you ever actually read this little piece of legal jargon? They say things like "we do not collect personal information from your computer" and "this program may install additional software used to verify your right to use the software". But who is checking to ensure that they are not, in fact, inadvertantly or otherwise, viewing your personal data? That is the issue. Who is watching the watchman?
While their programs look glitzy and easy to use, Microsoft is turning consumers into force-fed cash cows sitting at the end of a conveyer belt with their mouths and wallets wide open. We are being fed 'necessary' software and upgrades like candy while all the time, these same programs are being engineered and designed to block out competitor's products and keep us dependent on Microsoft. Never mind the fact that their software is so badly written that popup advertising and viruses infect computers and businesses everyday. Their software follows industry standards only when people scream for it. All these things actually hurt you, the consumer, because they severly reduce your choices when you want to use something other than Microsoft products. This is the problem with proprietary companies controlling what you run on your computer.
Microsoft keeps the lid to their inner workings welded shut very tightly. You will never truly know what is going inside of your Windows operating system. With the upcoming release of Longhorn things become even more cryptic and hidden as Gates and company begin to integrate privacy software into Windows called Digital Rights Management (DRM) and Trusted Computing. Eventually, every windows user will be restricted in what they can read, download, send or execute. One of the first signs of this change was the introduction in Windows 95 of the Windows Registry. The Registry is a mess of hidden settings and undocumented data that everyone objected to when Windows 95 was released. But Microsoft controls Windows. And what Microsoft says, goes. And because so many people run Windows, they eventually stopped complaining and accepted the change. The changes are still happening and consumers are blindly accepting it. If you really trust Microsoft with your finances, personal details and everything else stored on your computer, then you may sleep easy at night.
Enter the Linux operating system.
Linux, in contrast, let's you dig into the insides and see what it does, if you choose to do so. Even if you don't, you can rest assured that others in the Linux community are looking under the hood and making sure that it is safe and sound. Anyone can determine for themselves exactly how things work inside because it's developed in the open and nothing is 'welded' shut. In Linux there is no obfuscated and mysterious thing like the Windows Registry. It is all laid out in the open in plain text files. If DRM or Trusted Computing is implemented in Linux, it is done so by the community in such a way as to protect and enhance the Linux user, not to further tighten the stranglehold of a single company on your wallet and your freedom.
Linux is progress. It is about truth and freedom. It is about community and honesty. It is about open standards. It is about creating an alternative for the consumer that can be trusted and relied upon. It is certainly NOT about your wallet or the profit driven interests of a single company. Linux is growing day by day and it has become a full blown revolution.
So, to answer the question in the first paragraph, should you care? The answer is up to you.
To borrow from Isaac Asimov:
There is a single light of linux. To brighten it anywhere is to brighten it everywhere.