This chapter examines the mechanical strength of rocks, essential for understanding their response to external forces. It covers key properties such as uniaxial compressive strength (UCS), tensile strength, and shear strength, crucial for civil engineering, geology, and mining. Factors affecting rock strength—composition, structure, and environmental conditions like moisture and temperature—are discussed, alongside standardized testing methods like UCS and Brazilian tests. These methods inform engineering design, stability analysis, and construction practices across diverse geological contexts. Rock mechanics involves evaluating shear strength, compression characteristics, point load strength, abrasion resistance, hardness, and physical properties such as porosity, specific gravity, and moisture content. Methods like plunger-based shear testing and compression machines highlight how rock behavior varies under stress, emphasizing the need for standardized testing. Innovations in point load apparatus and abrasion testing machines enhance understanding of rock durability. Non-destructive techniques like the Schmidt hammer assess rock hardness under different conditions. Measurement of Young's modulus and Poisson's ratio provides crucial data for rock classification in engineering. Accurate determination of physical properties through testing and statistical analysis contributes significantly to geological and engineering assessments, offering insights into rock suitability and performance under diverse environmental conditions.