STL (file format)

An STL file format is like a special kind of document that tells a 3D printer what to make. It is made up of a lot of little triangles that fit together like a puzzle to make a 3D shape. Just like you can color in a picture on a flat piece of paper, 3D printers can use this file to make a 3D shape out of materials like plastic or metal. The STL file format is kind of like a recipe that the 3D printer can read to make something that you designed on the computer.