Wikipedia is, without doubt, the greater existing encyclopedia online nowadays. Count with more than one hundred thousand articles in Spanish, more of a million in English, and great amount in other languages. Altogether, articles of Wikipedia in 209 languages exist, plus other 5 of new creation, of which not yet no article exists. The creation method is simple, and cheap trustworthy: anyone can publish any article. The changes that a person always makes will be reversible, reason why the readers can publish articles freely, without no fear, since these later will be reviewed before their acceptance. The only restriction is not to spoil the articles, only write if really you know of the subject on which you are writing. Also, which is advised that connections within articles to other articles of Wikipedia are put, makes pleasant and interactive the consultation. The foundation that carries out Wikipedia has to end other projects based on he himself system, that so good result has given them in this occasion. These are, among others: Wiktionary (dictionary online), Wikiquote (famous appointments), Wikisource (gratuitous bookstore), Wikispecies (listed of species).