This paper gives an overview of the rapid evolution of parametrics, from somewhat slow beginnings in academic labs to mainstream commercial CAD. Although not recognized by the user community, parametric CAD is not a single technique but a set of techniques, each with its own advantages and limitations. Each is supported by different technologies. Most CAD systems allow one to mix and match different parametric approaches for creating part geometry. One objective of this article is to establish a clear terminology of parametric paradigms. An enumeration of parametric capabilities for model creation in current commercial CAD systems is reviewed. The influence of model history and constraint solving techniques on parametric modeling is also examined. Limitations exist in feature validation, unexpected model behavior due to topology changes, and solving coupled constraints at full 3D variational level. The idea of "assembly features" has not yet been exploited in commercial CAD. The discussion in this paper is a generalization of parametric capabilities of commercial systems; prototypes in academic research labs are not discussed.