Minecraft wiki entry for Development_versions, associated text: Comes in the 16 traditional dye colors
Smelt any colored stained clay in a furnace to obtain the glazed terracotta of that color (not for regular hardened clay).
Can be placed in 4 directions: north, south, west, and east.
When placed down while facing the right directions, a repeating pattern can be created. For example, the white glazed terracotta will create the pattern of a sun when 4 are placed down correctly.