A foundation is a substructure on which you build a structure. The foundation actually supports the building. In fact, each part of the building depends on the foundation. If it has good foundations, the building will stand.
Almost all buildings, regardless of their size, shape, intended purpose, type of construction or geographic location, share a common problem: they rest on the ground. Thus the design of adequate foundations is a general problem in building design. Since each building site is essentially unique in terms of specific geological conditions, each foundation present unique design problem.
A foundation is the connecting link between the structure proper and the soil. It is not visible to the public eye. It is a part of structures, which is usually placed below the surface of the ground (substructures) and transmits the load to the underling soil or rock. All soil compress noticeably when loaded causing the supported structure to settle. The main function of foundation is to transmit safety the high concentrated column or wall reaction to the ground without causing soil failure or unsafe differential settlement of the supported structure.
Design of foundation involves a soil study to establish the most suitable type of foundation and structural design to determine the proportion of the foundation elements.