Geometric Dimensioning and Tolerancing (GD&T): is a language of symbols and standards designed and used by engineers and manufacturers to describe a product and facilitate communication between entities working together to manufacture product.
Tolerances in engineering are an allowable amount of variation of a physical dimension. It’s important to keep tolerances on engineering drawings in perspective.
GD&T is an entirely new way of describing the dimensions and tolerances compared to traditional plus/minus tolerancing. Fundamentally, the engineer designs a part with perfect geometry in CAD, but the produced part is never perfect. Proper use of GD&T can improve quality and reduce time and cost of delivery by providing a common language for expressing design intent.
The benefits of Geometric Dimensioning and Tolerancing (GD&T) are: