4chan is the most popular English-language imageboard community with over 700,000 posts per day made by roughly seven million daily visitors. The site consists of 56 topical imageboards that are sectioned into six major categories: Japanese Culture, Interests, Creative, Adult Content and Miscellaneous and Others. The /b/ and /v/ board are considered the most active. It is known to be the birthplace of many of the memes on the internet, such as the Lenny Face, and Expand Dong.
It's also known to be very strange, allowing people to anonymously discuss certain topics. This can lead to many flame wars and arguments.