Hadron collisions refer to collisions between particles made up of quarks, such as protons and neutrons. These collisions occur in particle accelerators, where beams of hadrons are accelerated to high speeds and made to collide with one another. The purpose of studying hadron collisions is to understand the fundamental particles and forces that make up the universe. By studying the particles and energies produced in these collisions, scientists can gain insight into the fundamental structure of matter and the mechanisms by which particles interact with one another. This research area is essential for advancing our understanding of particle physics and cosmology.