The Wikipedia
The Wikipedia is a public effort to create a free multilingual web-based encyclopedia and it is a means to preserve public knowledge. The principles of open access and co-creation, which the Wikipedia operates on, have contributed towards its rapid growth in users and articles.
According to Yochai Benkler, Professor of Law at Yale University Law School, the Wikipedia adopts the system of 'commons-based peer production,' In addition, the diversity of motivated Wikipedians contributing to the online encyclopedia also allows the Wikipedia to create knowledge in more areas and in greater depth compared to traditional paper-based encyclopedia which has fewer resources.
Compare the Wikipedia and the Encyclopedia Britannica Online