The charm quark is one of the six types of quarks, which are fundamental particles that make up protons and neutrons. It has a positive electric charge of +2/3 and is denoted by the symbol "c." Charm quarks are heavier than up and down quarks but lighter than top and bottom quarks. They play a crucial role in the formation of certain particles, such as charmed mesons and charm baryons. Charm quarks were first proposed in the 1970s as part of the quark model to explain the properties of particles observed in high-energy physics experiments. They are essential for understanding the strong force, which binds quarks together within hadrons. The study of charm quarks helps physicists explore the fundamental forces of nature and the behavior of matter at a subatomic level.