Mechanical properties refer to the characteristics of materials that describe their behavior under various forces and loads. These properties include strength, elasticity, ductility, and hardness, which help determine how a material will react when subjected to stress. For example, steel is known for its high strength, making it ideal for construction, while rubber is elastic, allowing it to stretch and return to its original shape. Understanding mechanical properties is crucial in engineering and design, as they influence the selection of materials for specific applications. By knowing how materials like aluminum or concrete will perform under different conditions, engineers can create safer and more efficient structures and products.