Foundations carry and distribute loads from structures to the ground to prevent excessive settlement. There are several foundation types including strip, pad, and raft foundations which can bear directly on the ground or be supported by piles. The choice depends on ground conditions and the structure's layout and loading. Pad footings support single columns while strip footings support load-bearing walls or closely spaced columns. Raft foundations distribute loads over a large area for poor soil conditions. The document provides an example of designing a square pad footing to support a column based on loadings and soil capacity.