The Mohr-Coulomb Theory is a fundamental concept in soil and rock mechanics that describes the shear strength of materials. It states that the shear strength is determined by the material's cohesion and the normal stress acting on a failure plane. This relationship is often represented graphically using the Mohr Circle, which helps visualize stress states and failure conditions. In practical applications, the Mohr-Coulomb failure criterion is used to predict when materials will fail under various loading conditions. Engineers and geologists apply this theory to design stable structures, assess landslide risks, and evaluate the stability of slopes and foundations.