Surveying is the science and practice of measuring land to determine exact locations, distances, angles, and boundaries. When builders plan a new road or bridge, surveyors arrive first with precise instruments to measure the terrain, mark where construction should happen, and make detailed maps. When neighbors disagree about where their property line runs, a surveyor may help settle the dispute by measuring and marking the boundary.

Surveyors use tools like theodolites (instruments that measure angles with extreme accuracy), GPS devices, and lasers to create measurements accurate to within inches over distances of miles. Ancient Egyptians used early surveying techniques to build the pyramids and rebuild farm boundaries after Nile floods. George Washington worked as a surveyor before becoming president, mapping the Virginia wilderness.

The word also means examining something broadly to understand it better. A teacher might survey her classroom to see how students are doing, or you might survey your options before choosing an elective. When researchers conduct a survey, they ask many people questions to learn about opinions or behaviors.