An STL file is a wireframe representation of an object using a list of triangles. The triangles are represented as 3 coordinates in 3D space.
STL files are an open file standard and are widely used in Computer Aided Manufacturing (CAM) and rapid prototyping. The STL file format is good for printing out parts because it describes a part's surface geometry. Unfortunately, STL files are terrible for doing Computer Aided Design (CAD). They can be imported into CAD applications but are difficult to change. See the link to the article 'CAD vs CAM' in the discussion section below.
- ""CAD" files vs CAM files - a designer's plea". ... "STLs are to CAD models as a PDF full of photographs of words is to a text file. You can send them both to a printer just fine, but it's a big hassle to fix a typo." ... "the .scad files contain formulas that document what we in the SolidWorks community call "design intent"." ...