What language is Wikipedia programmed in?
Interestingly, you can answer this in wikipedia (It PHP).
It uses PHP / MySQL , in combination with MediaWiki software .
This is the same as all Wikimedia projects - Wiktionary , Wikinews , Wikiquotes , etc.
MediaWiki also involves many, many other sites - you can usually tell by appearance. Chief Wikia
It is programmed in PHP.
Wikipedia runs on MediaWiki software that uses PHP and MySQL (although MediaWiki may currently support other SQL databases, such as PostgreSQL, you will need to check the documents).