This textbook has been written for anyone whose work requires them to communicate, interpret or manufacture products through the use of engineering drawings and/or CAD models that use Geometric Dimensioning and Tolerancing. Readers will learn the new ASME Y14.5-2018 standard on Dimensioning and Tolerancing, as well as the differences between that standard and prior revisions of Y14.5. It teaches the new Y14.5 symbology, rules and basic principle revisions that the Y14.5 committee took 9 years to complete. The result of attaining this knowledge is that: product representations are able to be more specific in conveying functional requirements, products can be more easily manufactured, and appropriate inspection techniques are clear. Designers, manufacturing engineers, quality engineers, inspectors, product engineers and process engineers are just a few of the job categories that can benefit from the material contained in this textbook. Even those who have been trained in GD&T will need to be made aware of the changes that have been instituted into this latest Y14.5 revision. This book covers all of the basics on how to interpret, apply and measure GD&T per ASME Y14.5-2018.