Geometry validation is the process of checking a model for errors, gaps, and inconsistencies before it is used. In 3D workflows, this can include checking that a mesh is closed, surfaces are correctly oriented, dimensions are as expected, and the shape matches the intended design.
Validation matters because an STL can open successfully while still containing defects that cause problems during slicing, printing, or fabrication. Mesh-editing tools may repair holes or alter surfaces, but the result should be inspected and checked against requirements before production. In cyber security, the same principle applies to digital models used in manufacturing: validating inputs helps catch unintended or harmful changes before they affect physical systems.