This document discusses different measurement systems and measuring tools used in automotive work. It covers the metric and United States customary measurement systems, including common unit conversions between the two. A variety of measuring tools are then described, such as micrometers, dial indicators, calipers, and depth gauges used to accurately measure lengths, distances, and sizes. The document concludes by explaining common automotive fasteners like bolts, nuts, rivets and rings that hold vehicle parts together, as well as gaskets and seals that prevent fluid leakage between components.