File type: STEP 3D CAD
The STP file extension is used for 3D or three-dimensional assembly files containing pieces of three-dimensional or 3D object data. This file format is supported by different mechanical design programs or applications as an exchange file format of 3D product models.
The files with this format are saved in the ASCII or text-based file format conforming to the ISO 10303-2xx STEP Application Protocols. Other than this, no information has been mentioned about the use or description of the .STP file type.