PLY is also known as the Stanford Triangle Format. It is a WaveFront Object-inspired format with the option of extensions describing additional features of a 3D model, including color and transparency.
The .ply file can be supplied as an ASCII text file or as a binary format. ASCII PLY is preferred for accessibility and archiving in the long term.
Not every software supports all extensions of the Polyon file format: it is possible that the data is not completely read, depending on the software used. That is why it is especially important with PLY that it is well documented which information the data contains.
Polygon file format is a preferred format for file type 3D.