Autodesk Revit is used mainly for 3d building modeling, for example in Architecture to draw home plans. Are 3d objects are smart, meaning they are tied together in plan, section and elevation. If you move the 3d door, it'll show up in the new location in elevation, for example. There's also smart data for material takeoffs and area calculations. The best part is coordinating Architecture with consultants like Structural, Mechanical, and Electrical to find clashes early. For example, seeing the mechanical duct can't go thru a Structural column, we can see it in 3d before it's a problem on the jobsite; therefore, saving a lot of money in mistakes and errors.