Heavy ion collisions refer to experiments conducted in particle physics, typically at particle accelerators, in which two atomic nuclei are collided with each other at very high energies. These collisions simulate the extreme conditions that are thought to have existed just after the Big Bang, allowing scientists to study the behavior of matter under extreme temperatures and pressures. The main goals of heavy ion collision research include investigating the properties of the quark-gluon plasma, a state of matter that is believed to have existed in the early universe and may still be present in the cores of neutron stars. Scientists also study the production and behavior of various particles created in the collisions, such as mesons, baryons, and exotic forms of matter like hyperons. Heavy ion collisions provide valuable insight into the fundamental forces and particles that make up the universe, as well as helping to test and refine theoretical models of the early universe. This research area is a crucial component of the field of nuclear and particle physics.