This guide covers the selection of the number of measurement points when using Co-ordinate Measuring Machines (CMMs) and gives advice on the compromise between accuracy and speed. It provides guidance on sampling criteria for standard features and advice on measurements that involves projections of features over long distances. It covers cleanliness, part loading/alignment and the effect of temperature, surface finish and geometry on the final results. It also contains information on basic measurement principles, common measurement requirements, CMM software functionality in relation to drawing requirements and good metrology practice when using CMMs with CAD data to inspect parts.