Pile foundations are deep foundations used to transfer the load of a structure to a lower, more stable layer of soil or rock. Piles are long, slender columns typically made of steel, concrete, or timber that are driven or drilled into the ground. Pile foundations are commonly used in construction projects where the soil at the surface is too weak to support the weight of the structure or where the structure must be supported at a significant depth. Research in the area of pile foundations typically focuses on improving the design, installation, and performance of piles to ensure the stability and safety of the structure they support. This research may involve various methods such as field testing, laboratory experiments, numerical modeling, and analysis of case studies.