Great Seal of the United States, also called Seal of the United States, symbolizes the sovereignty of the United States. The government adopted it on June 20, 1782. It uses the seal to authenticate important documents. European countries had long used seals, and the new nation signified its equal rank by adopting its own seal. William Barton, a specialist in heraldry, advised the committee that designed the seal. He designed most of the seal's reverse side. Charles Thomson, secretary of the Congress, prepared the design used on the face.