A drilled shaft is a type of deep foundation used in construction to support heavy structures. It is created by drilling a hole into the ground and then filling it with concrete. This method is often used when soil conditions are challenging or when a building requires significant load-bearing capacity. Drilled shafts can be reinforced with steel bars, known as rebar, to enhance their strength. They are commonly used for bridges, high-rise buildings, and towers, providing stability and durability. The process of installing drilled shafts is efficient and minimizes disturbance to the surrounding area.