anonymous textboard; anonymous message board
An Internet forum where users can post without revealing their identity; common in Japanese online culture.
When posting on an anonymous textboard, be careful not to include personal information.
掲示板 is a general bulletin board (physical or online), while 匿名掲示板 specifically allows anonymous posting.
Compound of 匿名 (とくめい, 'anonymous') and 掲示板 (けいじばん, 'bulletin board').