Wikipedia has been founded by the American Jimmy Wales in 2001. The principle of Wikipedia is based on the concept of Open Content. Wikipedia is a so-called suitcase word, it consists of: wiki, which comes from the Hawaiian language and means fast. Pedia comes from encyclopedia. Each user can write or alter articles in Wikipedia. Wiki is an interactive project, which can offer something for every user for free. Wikipedia is a non-profit organization; it exists by the voluntary cooperation of the users. More than 5,000 authors just in Germany write for Wikipedia. Worldwide, more than 300,000 users are actively registered to Wikipedia. Wikipedia can be found by the time in almost every language. The quality control is based on the principle, that it is assumed that users correct each other. The authors are expected to write in lexicon style, which implies that they represent a neutral position and that their texts are based on secure and verifiable sources. This principle of quality management doesn't really work. The strength of Wikipedia, the simple principle, that makes possible for everyone to write and to publish texts in Wiki, is also a weakness. If the most part of the editors isn't educated, so the quality of the articles has to suffer. The style of some authors is not appropriate for an encyclopedia. Moreover, even inadvertently or intentionally false information added in the encyclopedia. This led to a loss of the image of Wikipedia in the last months. Despite all the criticism of Wikipedia, it is one of the most popular websites in the world and is already on several occasions with the Grimme Online Award and other awards.