More often, for more significant commercial and industrial buildings some piling system in their foundation construction is usually used. Foundation piling services drive reinforcing elements into the ground, often many meters deep, to help keep the foundation and walls of a building level, stable, and resilient in the face of settling and ground movement. In times gone by, wood was often used for piling but has mostly been replaced by steel or metal variants, since wood tends to rot far faster than steel rusts or decays underground. Once foundation piles are driven and capped (either via pedestals or foundation walls), then the foundation can be poured around them, and the walls constructed. That is a simplified view of the foundation construction process, which has many more intricate steps, that can also vary based on all the factors discussed in the previous section.