Wikipedia is a free, online encyclopedia that allows anyone to create, edit, and contribute articles and information on a wide range of topics. It was launched on January 15, 2001, by Jimmy Wales and Larry Sanger. Wikipedia has become one of the largest and most popular reference websites on the internet, with millions of articles in multiple languages.

Here are some key aspects and information about Wikipedia:

1. Open Editing: Wikipedia follows a collaborative model of content creation. This means that anyone with internet access can edit most of its articles. This open editing model has both advantages and challenges, as it allows for a diverse range of contributions but also requires a system to manage quality and prevent vandalism.
2. Neutral Point of View (NPOV): Wikipedia’s content policies emphasize a neutral point of view, meaning that articles should be written without taking sides or presenting a biased perspective. Contributors are encouraged to provide verifiable, reliable sources to support the information they add.
3. Citations and References: Wikipedia places a strong emphasis on citing reliable sources for the information presented in its articles. This helps ensure the accuracy and verifiability of the content. Readers can check the sources provided to assess the credibility of the information.
4. Multilingual: Wikipedia is available in numerous languages, with each language having its own set of articles and contributors. The English version is one of the largest and most frequently visited, but Wikipedia is also available in languages ranging from Spanish and Chinese to Swahili and Arabic.
5. Notability: Wikipedia has guidelines for notability, which means that articles are expected to be about topics that are sufficiently noteworthy or significant to merit inclusion. These guidelines vary between topics and language editions.
6. Categories and Portals: Articles on Wikipedia are organized into categories and portals to help users navigate and find related information. Categories group articles by subject matter, while portals serve as entry points for exploring broader topics.
7. Community of Editors: Wikipedia has a dedicated community of volunteers who monitor recent changes, revert vandalism, and engage in discussions about content disputes and editorial guidelines. Experienced editors are often given additional privileges to maintain the quality of the content.
8. Media Files: In addition to text, Wikipedia hosts a vast collection of images, audio clips, and videos that can be used to enhance articles. These media files are typically uploaded under specific licensing terms to ensure their legal and ethical use.
9. Reliability and Criticisms: Wikipedia’s open editing model has been both praised for its accessibility and criticized for its potential to contain inaccuracies and bias. The Wikipedia community has implemented various measures to address these concerns, including strict sourcing requirements and dispute resolution mechanisms.
10. Sister Projects: Wikipedia is part of the Wikimedia Foundation, which also oversees several other projects, including Wikimedia Commons (a media repository), Wikibooks (a collection of textbooks), Wikinews (a news source), and more.

Wikipedia has had a profound impact on the way people access and share information online, and it continues to be a valuable resource for general knowledge and research across a wide range of subjects. However, users are encouraged to critically assess the information presented and consult additional sources for in-depth research.