Concrete masonry units (CMUs) are rectangular blocks made from concrete, commonly used in construction. They are known for their strength, durability, and fire resistance, making them ideal for building walls, foundations, and other structures. CMUs come in various sizes and shapes, allowing for flexibility in design and construction. These units are often used in combination with mortar to create sturdy walls. CMUs can also be insulated or hollow, providing options for energy efficiency. Their versatility makes them a popular choice in both residential and commercial building projects, contributing to the overall stability of structures.