Tolerancing is the systematic process of defining and specifying acceptable limits for variations in the dimensions, form, orientation, and location of physical parts and assemblies. As a research concept and methodological approach, it investigates the principles and techniques for quantifying, analyzing, and managing the impact of manufacturing and assembly variations on product function, performance, and interchangeability. Key characteristics include the application of geometric and dimensional specifications, tolerance stack-up analysis, and the optimization of tolerance specifications based on functional requirements, manufacturing capabilities, and economic considerations.