What does seal mean

Seal, used to print on the document to indicate the identification or signing of stationery, general seal will be stained with pigment and then printed, not stained with pigment, printed on the plane will be presented after the concave-convex known as the steel seal, some of which is printed on the wax or varnish, envelopes on the wax seal. Some are made of jade, metal, wood and stone. Chinese seals are one of the representatives of traditional Han culture.