This is the English language Wikipedia. Wikipedia is a multi-lingual project; as of November 2014, there were 288 Wikipedias in various languages and dialects. Each Wikipedia is assigned a two or three letter code that corresponds to its language. So, for example, the English Wikipedia's code is "en" and the English Wikipedia's Internet address is en.wikipedia.org, technically a subdomain of wikipedia.org. The codes largely come from two international standards for language codes. For full details and a sortable table of all Wikipedias, see List of Wikipedias.
There is also a Wikipedia in simple English found at simple