STEP is a file extension for a 3-D graphic file used by CAD software. STP stands for STandard for the Exchange of Product model data. 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.

Many manufacturers will request a STP or STEP file for pricing and designing molds or pricing manufactured parts for your invention or product.
Files with the .step extension are usually 3D model files created in the STEP file format. STEP stands for Standard for the Exchange of Product Data. This ISO standard exchange format is used to distribute 3D data files (such as CAD files) in a format that can be viewed by a variety of software applications.
The .step file extension is interchangeable with the .stp file extension.
The .step file extension is also used for PyDDR files.
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.
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