AUTODESK INVENTOR

Autodesk Inventor is the 3D parametric solid modeling package produced by U.S.-based software company Autodesk. It is the leading software package in the 3D mechanical design market outselling in nearest competition for the last 5 years in a row. It's nearest competitors are other CAD systems such as SolidWorks, Pro/ENGINEER, and Solid Edge.
Unlike AutoCAD, Inventor is based on the more advanced parametric modeling techniques used by products like SolidWorks and Pro/ENGINEER. Inventor accomplishes this using an approach that Autodesk calls "Functional Design."
Inventor users begin by designing parts. These parts can then be combined into assemblies or design within the context of an assembly. As a parametric modeler, it should not be confused with traditional CAD programs. It is used in design and engineering to produce and perfect new products. Whereas in non-parametric CAD programs the dimensions are geometry-driven, a parametric modeler allows the geometry to be dimension-driven. If the dimensions are altered, the geometry automatically updates based on the new dimension. This allows the designer to store their design intent within the model, whereas non-parametric modeling is more akin to a 'digital drafting board'. Inventor also has tools for sheetmetal part creation, welded part creation, and, starting with Version 10, a rendering and animation environment called Inventor Studio based on the mental ray rendering engine.