"Touchstone" is a term that refers to a standard or criterion used to evaluate the quality or authenticity of something. Originally, it described a black stone used by goldsmiths to test the purity of gold and silver. In literature, it often symbolizes a character or element that reveals the true nature of others. In the context of literature, "Touchstone" is also a character in William Shakespeare's play "As You Like It." He serves as a witty and clever fool, providing insight and humor throughout the story. His role highlights themes of identity and the nature of truth in human relationships.