A shallow foundation is a type of building foundation that is placed close to the ground surface, typically within a depth of 3 to 4 feet. It is designed to support structures by distributing their weight over a larger area of soil. Common types of shallow foundations include spread footings, slab-on-grade, and strip foundations. These foundations are often used for residential buildings and smaller structures where soil conditions are favorable. Shallow foundations are generally easier and less expensive to construct compared to deep foundations. They are suitable for sites with stable soil that can bear the load of the structure. However, they may not be appropriate for areas with poor soil conditions or where there is a risk of soil settlement, which could compromise the stability of the building.