A foundation is that element of the architectural structure which connects the structure with the ground, and transfer loads from the structure to the ground. Foundations generally are divided as shallow and deep. Shallow foundations, also called footings, are embedded a meter or near value into the soil. A deep foundation transfer the load of a structure deep down from the weak layer of topsoil to the stronger layer of subsoil below. Trough the years, piles used for this purpose were wood, later steel, reinforced concrete, and pre-tensioned concrete. Showed on a sketches are visually explained the types of foundations that exist and are mostly used. More information, on the link bellow.

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