Pions, or pi mesons, are subatomic particles that play a crucial role in the strong nuclear force, which holds atomic nuclei together. They come in three varieties: 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. Discovered in the 1940s, pions are essential for understanding the interactions between protons and neutrons within atomic nuclei. They are often produced in high-energy collisions, such as those occurring in particle accelerators or cosmic ray interactions, providing valuable insights into the fundamental forces of nature.