Ceramic tiles or azulejo can be seen all over Macau on the walls of buildings and other surfaces. The term azuejo or azulejo refers to a typical form of Portuguese painted, glazed, ceramic tile work. The themes that they are used to portrait are many and varied, though they were first developed in abstract designs and were used to decorate religious buildings. Most Portuguese ones are tinted blue. Techniques for making glazed ceramic tiles were introduced to the region by the Moors. The word azuelo originates from the Arabic az-azulayj or "little stone."