Customers, Engineering and Manufacturing companies want quality product in the market. Quality does not happen by accident. The quality is achieved by refined engineering. Uncertainity is considered as prime enemy in the engineering Drawing. The uncertainity is eliminated by adapting of tolerance analysis to optimize the tolerance and Geometric Tolerance to ease tighter manufacturing tolerance burden by providing bonus tolerances, while keeping the design function intact. In this white paper we will look at what is a tolerance, stack up analysis and geometric tolerance and its importance in product development.