I realized that I never captured what I learned about the nature of open source projects anywhere, so here’s one attempt to rectify this omission.
The way I understand the concept of “open source” is that it’s a way of running a software project. In this definition hides a gazillion of options, and I will try to lay them out in a spectrum. Understanding these options as a spectrum has helped me quite a bit in reasoning about software project strategy, and I hope this will be helpful for you, too.
As bookends for our spectrum, let’s position two radical alternatives: fully closed-source and fully open source projects. As an example that might resonate with Web developers, we can see that the late Internet Explorer fits very close to the fully closed-source extreme and Firefox is at the other side of the spectrum.
To place other projects on the line between these bookends, we need a couple of notches. I will define these notches loosely, and give them numbers. So, any project that you’re evaluating for their degree of open source, you can use the whole part of the number as the rough estimate of where a project sits within the spectrum, and then the decimal part to adjust more finely.