STL Stands for “stereolithography” – it is a 3D rendering that contains only a single color. STL has become the standard file format for all Additive Manufacturing processes. STL file is a mesh of tessellated triangles applied to the surface of CAD model.
CAD geometry is approximated as a set of triangular facets. The accuracy of the approximation is controlled by setting the number / size of triangles. The number of triangles (accuracy of geometry) also governs data processing speed.