Geometric Dimensioning and Tolerancing (GD&T) is a system for defining and communicating engineering tolerances. It uses a symbolic language on engineering drawings and computer-generated three-dimensional solid models that explicitly describes nominal geometry and its allowable variation.
What is tolerance in technical drawing?
Engineering tolerance is the permissible limit or limits of variation in: a physical dimension, a measured value or physical property of a material manufactured object, system, or service, other measured values (such as temperature, humidity, etc.).