"Geoprofessions" is a term coined by the Geoprofessional Business Association to connote various technical disciplines that involve engineering, earth and environmental services applied to below-ground ("subsurface"), ground-surface, and ground-surface-connected conditions, structures, or formations. The principal disciplines include, as major categories:

Each discipline involves specialties, many of which are recognized through professional designations that governments and societies or associations confer based upon a person's education, training, experience, and educational accomplishments. In the United States, engineers must be licensed in the state or territory where they practice engineering. Most states license geologists and several license environmental "site professionals." Several states license engineering geologists and recognize geotechnical engineering through a geotechnical-engineering titling act.

Although geotechnical engineering is applied for a variety of purposes, it is essential to foundation design. As such, geotechnical engineering is applicable to every existing or new structure on the planet; every building and every highway, bridge, tunnel, harbor, airport, water line, reservoir, or other public work. Commonly, the geotechnical-engineering service comprises a study of subsurface conditions using various sampling, in-situ testing, and/or other site-characterization techniques. The instrument of professional service in those cases typically is a report through which geotechnical engineers relate the information they have been retained to provide, typically: their findings; their opinions about subsurface materials and conditions; their judgment about how the subsurface materials and conditions assumed to exist probably will behave when subjected to loads or used as building material; and their preliminary recommendations for materials usage or appropriate foundation systems, the latter based on their knowledge of a structure's size, shape, weight, etc., and the subsurface/structure interactions likely to occur.

Civil engineers, structural engineers, and architects, feasibly among other members of the project team, apply the geotechnical findings and preliminary recommendations to take the structure's design forward. They realize these preliminary recommendations are subject to change, however, because – as a matter of practical necessity related to the observational method inherent to geotechnical engineering – geotechnical engineers base their recommendations on the composition of samples taken from a tiny portion of a site whose actual subsurface conditions are unknowable before excavation, because they are hidden by earth and/or rock and/or water. For this reason, as a key component of a complete geotechnical engineering service, geotechnical engineers employ construction-materials engineering and testing (CoMET) to observe subsurface materials as they are exposed through excavation.

To help achieve economies on their clients' behalf, geotechnical engineers assign their field representatives – specially educated and trained paraprofessionals – to observe the excavated materials and the excavations themselves in light of conditions the geotechnical engineers opined to exist. When differences are discovered, the geotechnical engineers evaluate the new findings and, when necessary, modify their design and construction recommendations. Because such changes could require other members of the design and construction team to modify their designs, specifications, and proposed methods, many owners have their geotechnical engineers serve as active members of the project team from project inception to conclusion, working with others to help ensure appropriate application of geotechnical information and judgments.

In other cases, geotechnical engineering goes beyond a study and construction recommendations to include design of soil and rock structures. The most common of these are the pavements that make up our streets and highways, airport runways, and bridge and tunnel decks, among other paved improvements. Geotechnical engineers design the pavements in terms of the subgrade, subbase, and base layers of materials to be used, and the thickness and composition of each. Geotechnical engineers also design the earth-retention walls associated with structures such as levees, earthen dams, reservoirs, and landfills. In other cases, the design is applied to contain earth, via structures such as excavation-support systems and retaining walls. Sometimes referred to as geostructural engineering or geostructural design, these services are also intrinsic to hydraulic engineering, hydrogeologic engineering, coastal engineering, geologic engineering and water-resources engineering. Geotechnical-engineering design is also applied for structures such as tunnels, bridges, dams, and other structures beneath, on, or connected to the surface of the earth. Geotechnical engineering, like geology, engineering geology, and geologic engineering, also involves the specialties of rock mechanics and soil mechanics, and often requires knowledge of geotextiles and geosynthetics, as well as an array of instrumentation and monitoring equipment, to help ensure specified conditions are achieved and maintained.

Earthquake engineering and landslide detection, remediation, and prevention are geoprofessional services associated with specialized types of geotechnical engineering (as well as geophysics; see below), as is forensic geotechnical engineering, a geoprofessional service applied to determine why a certain applicable type of event – usually a failure of some sort – occurred. (Virtually all geoprofessional services can be performed for forensic purposes, commonly as litigation-support/expert witness services.) Railway-systems engineering is another type of specialized geotechnical engineering, as are the design of piers and bulkheads, drydocks, on-shore and off-shore wind-turbine systems, and systems that stabilize oil platforms and other marine structures to the sea floor.

Geotechnical engineers have long been involved in sustainability initiatives, including (among many others) the use of excavated materials; the safe application of contaminated subsurface materials; the recycling of asphalt, concrete, and building rubble and debris; and the design of permeable pavements.