Charm quarks are one of the six types of quarks, which are fundamental particles that make up protons and neutrons. They have a positive electric charge of +2/3 and are heavier than up and down quarks. Charm quarks are denoted by the symbol "c" and play a crucial role in the formation of certain particles, such as charmed mesons and charm baryons. These quarks were first discovered in the 1970s during experiments at particle accelerators. The existence of charm quarks helped to confirm the Standard Model of particle physics, which describes the fundamental forces and particles in the universe. Their unique properties contribute to our understanding of matter and the interactions between particles.