What Is Wikipedia?

Wikipedia is a free, collaboratively edited online encyclopedia published in more than 300 languages, maintained by a global community of volunteer contributors, and hosted by the Wikimedia Foundation, a nonprofit organization incorporated in the United States. Founded in January 2001 by Jimmy Wales and Larry Sanger, Wikipedia grew from an experimental complement to the expert-authored Nupedia project into the largest reference work ever compiled, with over 67 million articles across all language editions as of 2026. The platform is built on the MediaWiki software and the wiki model of collaborative editing, in which any reader with internet access can create or revise content subject to community-defined policies.

Wikipedia occupies a distinct position in information science, computer-supported cooperative work, and knowledge management research. It represents a large-scale natural experiment in open production, demonstrating that a structured volunteer community can produce and maintain an encyclopedic resource at a scale and breadth that no traditional editorial organization has matched. Its articles, policies, and edit histories constitute one of the largest publicly available datasets for studying human collaboration, language, and knowledge representation online.

Collaborative Editing Model

Wikipedia's editing model allows any user, registered or anonymous, to modify most articles through a browser-based interface backed by the MediaWiki revision control system. Every change is logged with a timestamp and contributor identifier, and any version can be restored. The community governs content through a layered policy structure: core principles such as neutral point of view, verifiability, and no original research define what belongs in articles, while project-specific guidelines and talk-page consensus processes resolve individual disputes. A small number of articles are semi-protected or fully protected against editing by unregistered users, typically those covering contentious or frequently vandalized subjects.

Research on coordination among Wikipedia editors has examined how volunteer communities distribute labor, manage conflicts, and sustain contribution over time. A study published in ACM Transactions on Computer-Human Interaction analyzed collaboration patterns across thousands of articles, finding that article quality correlates with sustained participation by a diverse group of contributors rather than with any single editorial authority.

MediaWiki Technology Platform

MediaWiki, the open-source software on which Wikipedia runs, was developed in-house at the Wikimedia Foundation beginning in 2002 and released under the GNU General Public License. It provides a wiki markup language, a relational database backend, a revision history system, and a template engine that allows standardized infoboxes, citation formats, and navigation structures to be maintained consistently across millions of articles. The Wikidata project, a structured data repository also operated by the Wikimedia Foundation, supplies machine-readable facts that populate Wikipedia infoboxes in multiple languages from a single shared data source, reducing translation overhead and improving cross-language consistency.

Knowledge Representation and Reliability

Wikipedia articles are organized into a hierarchical category system and cross-linked through hypertext, making the encyclopedia a large-scale hyperlinked knowledge graph. Researchers in natural language processing, information retrieval, and machine learning have used Wikipedia as a training corpus and entity knowledge base, with applications including named entity recognition, question answering, and knowledge graph construction. Studies of article accuracy have found that Wikipedia's coverage of scientific topics is generally comparable to that of traditional encyclopedias in breadth, though individual articles vary widely in depth and currency. The Springer journal Scientometrics has published research examining how scientific knowledge propagates through Wikipedia and how citation practices in academic literature relate to Wikipedia content.

Applications

Wikipedia has applications in a range of fields, including:

• Natural language processing corpora for training text classification and language models
• Knowledge base construction for question-answering and information retrieval systems
• Science communication and public understanding of technical topics
• Reference support for journalists, educators, and researchers needing quick orientation
• Cross-lingual information access through coordinated multilingual article networks