STL, an abbreviation for stereolithography, 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.
XLAM files are used to extend the modules provided by Excel. They can be added to Excel 2007 or later, or to earlier versions of Excel with Open XML component support. File used by Microsoft Excel, a program that allows users to create and edit spreadsheets; contains a macro-enabled add-in, which provides extra functionality and tools that may execute macros.
You can also convert STL into many other file formats. Please see the complete list below.