Source Description
Wikipedia(en) Contains over 6 million articles written by non-specialists. Leans politically left and usually has a western perspective. Often has poor coverage of youtubers, flash games, meme culture, foreign authors, and politics of countries that do not speak english. Information is frequently updated.
Encyclopedia Britannica Contains less information than wikipedia, and is not as frequently updated. Articles are written by top academics for impressive accuracy and balance. Articles from over 200 physical reference works of great quality. Poor coverage of events and developments in the last 20 years.
Rationalwiki Decidedly left wing encyclopedia with a focus on media and internet culture in the United States and the anglosphere. Over 7000 articles.
TV Tropes Contains thousands of tropes and works.
Know Your Meme 20'000 articles about meme culture.