It is the kernel of the operating systems that engineers at Red Hat and others, including the Debian team, build. It is the poster boy of a movement much larger than operating system kernels, operating systems, Internet Server applications or any other specific technology. I would still be operating out of our spare bedrooms. But it's not. Open source delivers a benefit to its users that they cannot get from any of the suppliers of proprietary binary-only products like Windows.
Open source gives the user the benefit of control over the technology the user is investing in.
This benefit is perfectly obvious to every programmer and system administrator I've ever spoken to, but it is sometimes tough for nontechnical journalists to grasp. The best analogy that illustrates this benefit is with the way we buy cars. We demand the ability to open the hood of our cars because it gives us, the consumer, control over the product we've bought and takes it away from the vendor. In the proprietary software business, the customer has no control over the technology he is building his business around. If his vendor overcharges him, refuses to fix the bug that causes his system to crash or chooses not to introduce the feature that the customer needs, the customer has no choice.