What is the term for art made from small pieces of glass or tile?

A mosaic is an art form created by assembling small pieces of coloured glass, tile, stone, or other hard materials (called tesserae) into a pattern or image. The pieces are set into a binding medium such as mortar or adhesive on a surface. Mosaics have been used since antiquity for decorating floors, walls, and ceilings.

A collage involves gluing various materials (paper, fabric, photographs) onto a surface, but the materials are not necessarily small uniform pieces of glass or tile. A fresco is a mural painting technique in which pigment is applied to wet plaster on a wall. Relief is a type of sculpture that projects from a background surface, not a technique involving small pieces of glass or tile.