Veneers are Thin layer (about .5 to.7 mm thick) of either composite or ceramic put or stuck on teeth. It is done to enhance smile, cover mildly discoloured teeth, to close spaces between teeth, reshape the teeth, to cover small enamel defects, to treat teeth in slightly malposition to make them look more straight, to cover up poor restorations, to cover wear patterns, etc. It's an excellent treatment to improve smile with very minimal grinding of teeth. Sometimes it's a very good alternative to making full crowns which involves grinding of teeth all around.