A free-form 3D modeling application known for its ease of use, popular for early massing studies and concept design before a project moves into Revit. Many architecture students and small firms start a concept in SketchUp because its learning curve is far gentler than Revit's parametric approach - the tradeoff is that a SketchUp model carries no real building data (no wall types, no schedules), so it typically gets rebuilt as proper Revit families once the design is set, rather than imported wholesale.