Geotechnical drilling is a type of drilling that is performed as part of the construction process. This is mainly for structures such as buildings and oil rigs, or as part of the investigation process carried out on site prior to construction. The type of drilling equipment used to perform the work will depend upon the specific requirements of the project. Drilling rigs are the machines that are used to create holes in the ground. They vary in size and capabilities, ranging from massive structures that house equipment used to drill oil wells, to rigs that are small enough to be moved manually by one person, called augers. Mobile drilling rigs can be mounted on a truck, track or trailer, while the larger drilling rigs such as those used in offshore oil rigs are more permanent structures.