Point a telescope at a target. Read an angle off a scale. Walk out, measure a distance with a tape or a chain. Write both numbers in a field book. Repeat for the next point. That was surveying for most of the 20th century, and it was slow, and it was easy to get wrong.

A total station collapses that whole process into one instrument. It is, at its core, a digital theodolite (for angles) fused with an electronic distance measuring unit, or EDM (for distance), plus a small onboard computer that does the trigonometry instantly. Aim it at a target, press a button, and it hands you an angle, a distance, and often the full x, y, z position of that point, all in one reading.