Encyclopædia Britannica

An encyclopedia (also known in English as an encyclopædia) is a collection (usually a book or website) of information. Some are called "encyclopedic dictionaries".

All encyclopedias were printed, until the late 20th century when some were on CDs and the Internet. 21st century encyclopedias are mostly online by Internet.The largest encyclopedia in the English language is English Wikipedia, which has more than 6 million articles. The second largest is the Encyclopædia Britannica, which is the largest one that is printed. Either kind of encyclopedia can inform us on many different topics.