Long-lived particles are hypothetical particles that have extremely long lifetimes compared to other particles in the Standard Model of particle physics. These particles can exist for seconds, hours, or even longer before decaying into more familiar particles. Long-lived particles are of interest to physicists because they may provide clues to new physics beyond the Standard Model, such as dark matter, supersymmetry, or extra dimensions. Research into long-lived particles involves studying their production, detection, and properties in particle accelerators, cosmic ray experiments, and astrophysical observations. Experimental techniques such as calorimeters, time-of-flight detectors, and specialized triggers are used to search for the signatures of long-lived particles in high-energy physics experiments. The discovery of long-lived particles could have profound implications for our understanding of the universe and the fundamental forces that govern it. By studying these elusive particles, physicists hope to uncover new physics that lies beyond our current understanding.