Answer:
A deep foundation is a type of foundation that is used to transfer building loads to a deeper level within the Earth's subsurface when the shallow soil near the surface is not able to support the structure's weight effectively. Deep foundations are commonly used in construction projects for tall buildings, bridges, and structures where the soil conditions at the surface are not suitable for supporting the loads. There are various types of deep foundations, and two primary categories are piles and drilled shafts.