Fatigue life is a key concept in the field of materials science and engineering, particularly in the study of materials under repetitive or cyclic loading conditions. It refers to the number of cycles or repeated stress that a material can endure before it fails. Understanding fatigue life is crucial in designing and predicting the durability of materials and components in various applications, such as structural engineering, aerospace, automotive, and biomechanics. Researchers study the mechanisms of fatigue failure and develop techniques to enhance the fatigue life of materials through material selection, design optimization, and surface treatments.