Your large assemblies will thank you for attending this presentation! There are many reasons why models imported from IGES, STEP, or Parasolid files have errors. CAD products used for creating geometry "speak" different languages, and in order to understand each other, they need translators. Whenever you get an extra link in the communication chain, bits of information could be lost, and topological errors could be introduced. Examples: gaps in the body, self-intersecting faces, faces with more than one closed contour, faces that are piercing the solid body. Once the errors are identified they must be repaired, otherwise the consequences can be severe: long opening and saving times for assemblies and drawings containing those components, graphics glitches, rebuild errors and even crashes. We will also show that the tools and techniques used for identifying and fixing import errors can be repurposed for simplifying complex geometry. Your assemblies will thank you!