File with a .PLY extension contains a 3D image stored with headlines and sets of apexes of polygons which compose an object. It is compliant with the Polygon File open format. File can also store properties of each polygon, such as colour, transparency or information on textures.

PLY files come in two versions – text and binary, however, the headline of a file is always stored in the ASCII code. It is used by many 3 D graphic applications. The format was developed in the 1990s at the Stanford university, and it was based on the OBJ format. It is also called the Stanford Triangle Format