Bricks are rectangular blocks made primarily from clay that are hardened through firing in a kiln. They have been used in construction for thousands of years due to their durability, strength, and versatility. Good brick material contains 20-30% alumina, 50-60% silica, up to 5% lime, and 5-6% iron oxide, which provide cohesion, prevent cracking, and impart color. Bricks are manufactured by preparing soil through removal of debris, blending additives, tempering with water, molding, drying, and burning in kilns to produce hardness and strength through physical and chemical changes.