Imageboard
About
An imageboard is a type of forum that focuses on images embedded into posts. The first imageboards were Japanese, but today there are imageboards in many other languages, as well, such as English.
Most English-language imageboards are centered on Japanese culture.
Some of the most well-known imageboards include – but are not limited to – 2ちゃんねる / 2channel (often abbreviated as "2ch"), ふたば(双葉)☆ちゃんねる / Futaba Channel (a.k.a. 2chan), 4chan, 8chan, Krautchan, and 420chan.
The imageboard 4chan has more than 2 billion posts as of 2016. Nearly 3 million posts are posted to 2channel every day.
Features
Most imageboards out there allow their users to send messages anonymously, and no registration is necessary. In some cases, logging in is not even possible.