The symbol "π+" represents a type of subatomic particle known as a positive pion. Pions are mesons, which are particles made of a quark and an antiquark. The positive pion consists of an up quark and a down antiquark, giving it a positive electric charge. Pions play a crucial role in mediating the strong nuclear force that holds atomic nuclei together. Positive pions are produced in high-energy processes, such as cosmic ray interactions and particle collisions in accelerators like the Large Hadron Collider. They have a relatively short lifespan, decaying into other particles, including muons and neutrinos. Understanding pions helps physicists explore fundamental forces and the structure of matter.