Wikipedia is a multilingual open-collaborative online encyclopedia created and maintained by a community of volunteer editors using a wiki-based editing system. It is one of the 15 most popular websites as ranked by Alexa, as of January 2021 and "The Economist" magazine placed it as the "13th-most-visited place on the web".
With 6.2 million articles, the English Wikipedia is the largest of the more than 300 Wikipedia encyclopedias. Overall, Wikipedia comprises more than 55 million articles, attracting 1.7 billion unique visitors per month.
Here is a video showing how Wikipedia can be used for research.