STL, abbreviation for stereolithrography, is an interchangeable file format that represents 3-dimensional surface geometry. The file format finds its usage in several fields such as rapid prototyping, 3D printing and computer-aided manufacturing. It represents a surface as a series of small triangles, known as facets, where each facet is described by a perpendicular direction and three points representing the vertices of the triangle.
Files with PPSM extension represent Macro-enabled Slide Show file format created with Microsoft PowerPoint 2007 or higher. Another similar file format is PPTM which differs in opening with Microsoft PowerPoint in editable format instead of running as Slide Show. When run as slide show, the PPSM file shows the presentation slides with contents intact in the slide show and is in read-only mode by default. PPSM files can still be edited in Microsoft PowerPoint by opening it in PowerPoint.
You can also convert STL into many other file formats. Please see the complete list below.