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Geometric Dimensioning and
Tolerancing (GD&T)
Overview
Engineers communicate with mathematical formulas and blueprints (draw-
ings). Since the early days of humans, mathematical formulas have been
improved and have stood the test of time. We have indeed learned how
to communicate with numbers at a very sophisticated level. However, the
second form of communication for engineers—blueprints (drawings)—has
been drastically changed because of different interpretations that humans
put on the pictures. The mathematical foundation of this change started
in the late eighteenth century when Gaspard Monge solved the problem of
“two-dimensional rep