Computer-aided design (CAD), also called computer-aided design and drafting (CADD), is a process of using computer technology to create two- and three-dimensional representations of physical objects for use in industrial engineering, manufacturing, and many other industries. Many software companies, such as Autodesk and SolidWorks, have created different CAD programs to support the various design needs of architecture, engineering, and design companies and the government. This list explains the differences between the downloadable file formats available for viewing, editing, saving, transferring, or printing two- or three-dimensional technical drawings and CAD designs.

• .dwg, for Drawing (DWG), is an Autodesk file format for storing two-dimensional design data with its metadata. DWG is the native file format for AutoCAD, Caddie, and several other CAD applications. This common file format is also supported by ArchiCad, Adobe Illustrator, and TurboCAD.
• .dxf, for Drawing eXchange Format (DXF), is an Autodesk file format that allows for data exchange between AutoCAD and other programs. DXF provides a near-exact two-dimensional representation of the data in a DWG file, but does not support some objects, such as ACIS solids.
• .edrw, for eDrawings (EDRW), is a SolidWorks file format that is commonly used to reduce a file’s size for transferring three-dimensional design data through e-mail or the Internet. Many CAD programs, such as AutoCAD, Catia, and Google SketchUp, can publish and open EDRW files.
• .igs, for Initial Graphics Exchange Specification (IGES), is a vector file format that allows the digital exchange of information from one CAD program to another. IGES uses ASCII text data to exchange wireframes, solid models, and other three-dimensional engineering and manufacturing drawings among different CAD programs. Many CAD programs, such as TurboCad, AutoCAD, and VectorWorks, can write to and open IGES files.
• .pdf, for Portable Document Format (PDF), is an open standard file format for document exchange. PDF files display the same, regardless of application software and operating system requirements. There are two kinds of PDF files. 2D PDF files are static or flat, and display a document's text and two-dimensional images. 2D PDF files do not allow for manipulation of objects within the document like a CAD file does. 3D PDF files display interactive three-dimensional models that may be rotated or otherwise manipulated for closer examination. Many CAD products, such as AutoCAD and SolidWorks, can export data to a 3D PDF.
• .sldprt, for SoLiDworks PaRT (SLDPRT) file, is a SolidWorks file format that displays a three-dimensional object or part that may be combined with another part as an assembly and animated to view potential conflicts. SolidWorks can view, and save to, a SLDPRT file; Adobe Acrobat can also view SLDPRT files.      
• .stp, for STandard for the Exchange of Product (STEP) model data, is an International Organization for Standardization (ISO) 10303 standard file format for three-dimensional product manufacturing information that is independent of all programs and operating systems. STEP is commonly used to exchange data among many computer-aided drafting, manufacturing, engineering, and product data management systems.