Over at Sphere of Networks, I published a text that tries to give a simple overview of the workings of information production in the age of the internet, covering everything from free software to free culture. This article is a slightly modified version of another chapter of this text. This time I will show you how the internet enabled a new form of information production: commons-based peer productions, like Wikipedia or most free software today. What is free content and why is it so important to people collaborating over the internet?