An STL file saves object data in a format used for stereolithography. STL files have a file-name extension of .stl. There is an ASCII STL format as well as a binary STL format. You can choose which to create when you export a 3ds Max Design scene.
STL files are generally used for purposes of rapid prototyping. A variety of methods use the STL format to construct prototypes. For example, many STL machines use a liquid polymer and harden it in small slices, creating a solid plastic model. Other STL machines use metal powder to create a model in steel. Still other machines use a special wax.