Wikipedia is a free-access, free-content Internet encyclopaedia, supported and hosted by the non-profit Wikimedia Foundation.
Wikipedia allows to search for and read Wikipedia articles written in any language, at the beginning of its existence Wikipedia articles could be edited by any reader, even those who did not have a Wikipedia account. However today e.g. English Wikipedia and some other Wikipedia’s gradually have restricted modifications (only registered users may create a new article). Modifications to all articles would be published immediately. As a result, any article could contain inaccuracies such as errors, ideological biases, and nonsensical or irrelevant text. Each article and each user of Wikipedia has an associated “Talk” page. These form the primary communication channel for editors to discuss, coordinate and debate.
Access to the service is free. Apps for IOS, Android and Windows Phone (for Windows Phone developed by mobile devices are available without any charge. Reviewing the Wikipedia resources is easy and possible via browser or dedicated apps however it requires the Internet access. Overall it is a widely used and highly popular encyclopaedia containing millions of articles in different languages.