Full form of Ag is Silver (or silver)
Silver (Ag), also known as silver is a chemical element in the boron group with symbol Ag and atomic number 47. It is a soft, white, lustrous transition metal. Most silver
is produced as a byproduct of copper, gold, lead, and zinc refining. It makes up about 8% by weight of the Earth's solid surface.
Silver metal is used industrially in electrical contacts and conductors, in mirrors and in catalysis of chemical reactions.
More information can be found at http://en.wikipedia.org/wiki/Silver