Sign
Signs are tiles that appear in both the Classic Trilogy and the Wonderland Adventures Trilogy.
Classic Trilogy
Signs can be read simply by stepping onto them. Sometimes the text on the sign is a hint for the level or to explain a puzzle, while other times it just adds to the level's atmosphere.
Wonderland Adventures Trilogy
In the Wonderland Adventures Trilogy, signs behave somewhat differently. They now look like actual signs instead of just pieces of paper on the ground. They are now read by clicking on them instead.