Mass hierarchy refers to the observed pattern of particle masses in the universe, particularly in the context of elementary particles like quarks and leptons. In the Standard Model of particle physics, these particles have a wide range of masses, with some being very light, such as electrons, and others being much heavier, like top quarks. This disparity raises questions about why these masses differ so significantly. The concept of mass hierarchy is crucial for understanding the fundamental forces and interactions in the universe. It also relates to theories beyond the Standard Model, such as supersymmetry and string theory, which attempt to explain the origins of mass and the relationships between different particles.