Erosion is the phenomenon of material degradation and loss from surfaces exposed to the extreme physical and chemical conditions inherent in nuclear environments, such as high-energy particle flux, elevated temperatures, and reactive coolants or plasma. This concept is a core research area within nuclear materials science and engineering. It investigates the specific mechanisms responsible for surface deterioration and material removal, including sputtering, blistering, embrittlement, corrosion, and thermal fatigue under irradiation. Key characteristics involve the progressive alteration of surface morphology, microstructural changes, and degradation of mechanical properties. Its significance lies in its critical influence on the structural integrity, operational lifespan, and safety of nuclear reactor components, fusion device plasma-facing materials, and fuel claddings, necessitating rigorous study for design and material selection.