Started with the English-language version in January 2001 as an expansion of the previous Nupedia, the project soon reached an international nature and involvement. After six years, more than 174 Wikipedias are active around the world; the English version includes almost 3,800,000 entries, the other major ten languages (French, Japanese, Dutch, Italian, etc.) have between 400,000 to 1,355,000 entries — all of them rapidly growing. Each article, and related editing, is written only by volunteers on a variety of subjects – from society and culture to science and technology – and can be enriched and updated at any time. The global success of this initiative is based on its open and collaborative nature, along with the many tools and features gradually introduced in the project, including “featured articles”, the neutral point of view policy, navigation templates, and dispute resolution mechanisms such as mediation and arbitration. Despite some controversies about authors’ expertise and credibility, this on-going project has quickly become the symbol of free knowledge sharing and building enabled by the digital era. Structured as a traditional entry-based encyclopedia, Wikipedia is searchable by entry or topic and hypertextual links are extremely used, any time that a word corresponds to an edited entry. All contents can be saved, read and distributed under the GNU GPL license.