What What is Parametric Modeling?
Parametric Modeling is an approach to CAD that leaves the traditional 2 dimensional approach. Parametric modeling represents a different approach to CAD compared to 2D drafting.
It is often called Feature Based modeling. Parts are composed of features of positive or negative space. A positive space can be an extruded boss, a negative space can be a hole or segment that is cut away.
Often the feature is sketched 2 dimensionally and extruded, revolved or swept into a 3 dimensional object.
In 2D CAD designs were object driven. That meant if you changed the object the dimension would change. In Parametric Modeling designs are dimension driven. Change the dimension and the object will change.
In this system you sketch a feature and make it three dimensional. Objects of the sketch and dimensions can be "constrained". Constraints are elements that enhance design intent. Some common constraints are making sketch elements parallel, perpendicular, tangent, cooincident, horizontal or vertical. Mathematical equations can also be setup within dimensions and features can have a hierarchical relationship.