Sister Projects: Wikidata, Wikisource, and More That Power Wikipedia

When you think of Wikipedia, you’re probably thinking of the encyclopedia—but what you’re actually seeing is just one part of something much bigger. sister projects, a network of free knowledge platforms run by the Wikimedia movement that support, verify, and expand Wikipedia’s content. Also known as Wikimedia projects, these tools let volunteers build structured data, host original texts, and share media—all to make sure Wikipedia stays accurate, deep, and open to everyone. Without them, Wikipedia would be missing its foundation. You can’t cite a source if there’s no place to store it. You can’t compare facts across languages if there’s no central database. You can’t add images or audio without a free media library. The sister projects aren’t optional extras—they’re the hidden engines keeping the whole system running.

Take Wikidata, a free, collaborative knowledge base that stores structured facts like birth dates, population numbers, and geographic coordinates. Also known as the central knowledge graph, it connects over 300 Wikipedia language editions so that updating one fact—like the height of Mount Everest—automatically fixes it everywhere. That’s how a small-language Wikipedia can stay current without needing hundreds of translators. Then there’s Wikisource, a library of free, public-domain texts like old newspapers, legal documents, and classic books. Also known as the original source archive, it gives Wikipedia editors direct access to primary materials so they can verify claims instead of relying on secondhand summaries. And don’t forget Wikimedia Commons, the massive collection of free images, videos, and audio files used across all Wikipedia editions. Also known as the media hub, it’s where photos of historical artifacts, maps, and scientific diagrams live, making articles visual and trustworthy.

These projects don’t just support Wikipedia—they fix its weaknesses. Geographic bias? Wikidata helps balance coverage by letting editors from any country add facts about their region. Language gaps? Wikidata and translation tools let content flow between editions. Misinformation? Wikisource gives you the original document to check. Even tools like Huggle and the Wikipedia Library exist because the sister projects provide the data and access needed to make them work. You won’t find ads, corporate sponsors, or paywalls here. Just volunteers, open licenses, and a shared belief that knowledge belongs to everyone.

What you’ll find below is a collection of real stories showing how these sister projects shape what you read on Wikipedia every day—from how Wikidata keeps a small-language edition alive, to how journalists use Wikisource to dig up century-old records, to how educators rely on Commons to bring history to life in the classroom. These aren’t side projects. They’re the reason Wikipedia works at all.