Long-lived neutral particles are hypothetical particles that have extremely long lifetimes compared to the more familiar particles of the Standard Model of particle physics. These particles may be electrically neutral and interact very weakly with matter, making them difficult to detect in traditional particle detectors. Research on long-lived neutral particles is motivated by the search for new physics beyond the Standard Model, as these particles could provide evidence for phenomena such as dark matter or extra dimensions. Experimental searches for long-lived neutral particles typically involve high-energy particle colliders, such as the Large Hadron Collider (LHC), as well as underground detectors and astrophysical observations. The discovery of long-lived neutral particles would have significant implications for our understanding of the fundamental forces and particles of the universe, and could potentially lead to breakthroughs in our quest to unravel the mysteries of the cosmos.