π-mesons, also known as pions, are subatomic particles that play a crucial role in the strong nuclear force, which holds atomic nuclei together. They are classified as mesons, meaning they are made up of a quark and an antiquark. There are three types of pions: positively charged (π⁺), negatively charged (π⁻), and neutral (π⁰). Pions are relatively light compared to other mesons and have a short lifespan, decaying into other particles. They are important in particle physics and are often produced in high-energy collisions, such as those occurring in particle accelerators like the Large Hadron Collider.