The primary purpose of the Inchworm is to measure distances with a high level of accuracy. It achieves this by using a flexible line calibrated with precise marks. The line runs over a wheel at the end of the Inchworm's handle. As you pull the line out and extend it, the wheel rotates and precisely measures the distance. The Inchworm is commonly used in various industries for tasks like measuring distances for floor planning, installing carpeting, designing landscapes, and any precise measurement scenario where a tape measure may be less practical or accurate.