According to The Open Source Initiative, "Open source is a development method for software that harnesses the power of distributed peer review and transparency of process. The promise of open source is better quality, higher reliability, more flexibility, lower cost, and an end to predatory vendor lock-in." In lay terms, open source software is community-collaborative, which makes the code stronger and safer. Because of this, it's usually either free to individual users or much lower in cost than closed source products like Microsoft Windows, Office or FrontPage.
I wholeheartedly support open source software and the philosophy of community-collaborative development, software or otherwise, which is why my writing and my web site are open source driven. I recommend the following products: