The term 'Sign of Agreement' can refer to two common gestures used to signify agreement between two or more people. The first is a NOD, which is a short, quick movement of the head up and down to indicate agreement or understanding. The second is a HANDSHAKE, which is a gesture in which two people grasp each other's hands as a sign of agreement, greeting, or farewell. Both of these gestures are widely used around the world and have been for centuries.