STP stands for STandard for the Exchange of Product.
STP is a file extension for a 3-D graphic file used by CAD software. STP files are used to store 3D image data in an ASCII format, following the standards defined in ISO 10303-21 : Clear Text Encoding of the Exchange Structure.
STP files can be opened by CATIA (Computer Aided Three Dimensional Interactive Application), a commercial CAD software suite created by Dassault Systemes and marketed by IBM.
MIME type : application/vnd.ms-access
Learn more about .STP files:
Visit the CATIA web page.
See answers to CAD-related questions at ITKnowledgeExchange.com.