MediaWiki is the free and open-source wiki software that powers ProleWiki. It was developed in 2002 for use on Wikipedia, but since its codebase is open source, many other wiki sites use it. For example, Cuba's EcuRed, Leftypedia, and Wikispooks.
Given ProleWiki's reliance on MediaWiki, we advise our contributors to familiarize with their documentation. And if you're particularly technical, you could even contribute to the open source MediaWiki codebase which will eventually trickle down to ProleWiki (when we do our regular updates)