Signs

Signs are non-solid blocks that can display text. They also can be used in water elevators. Underwater they can be placed to generate "air" for the player.

They were first released in June 7, 2010, and are a common way for players to mark their existence/leave a legacy. Signs also work as communications e.g. thanking or asking other players. Signs also work as memos to display certain reminders or warnings.

Below is a list of over 1,300 signs in 2b2t circa Feb 2018. SalC1 made a cool video about 2b2t signs here (2019).