Disclaimer: OS here does not mean Operating Systems. It means Open Source.
Open Source. For the layman, here is the definition: Open source describes practices in production and development that promote access to the end product’s source materials.
The Operating System I use (Ubuntu) is open source. The blogging software I use (WordPress) is open source. The Office Suite I use (OpenOffice) is open source. The instrumental music I listen to (eg – Fairytale) is open source. And now, the study material I use for mathematics, is open source!
Open source is the revolution of, not just the future, but also the present! Hail Ho!
This is the simplest definition and description of open source that I've ever read on the Internet!!
OSS(Watch Spykids!!)