What is Open-Source Software?

Open-source refers to software whose license requires that its software code be open, extensible and freely distributable. It also allows for collaborative development, which refers to the worldwide community of software developers participating in a continuous cycle of development, review and testing over the Internet.

What are the differences between "Open Source" and "Free Software"?

Informit.com: Free Software vs. Open Source Software by David Chisnall
The terms "Free Software" and "Open Source Software" are often used interchangeably, and even abbreviated together as F/OSS (for "Free/Open Source Software"). Are there any differences between the two? If so, what are those differences? If not, why do the two different names exist? David Chisnall examines this paradox.

What are the benefits of Open-Source Software?

With open-source, the user is in control. Access to the source code makes software easy to configure to specific user needs. Because open-source is freely distributed, it can greatly reduce the user's total cost of computing. Open-source software is reliable, stable, scalable, secure and extremely cost-effective.