CAD (computer aided design) means computer-aided design. Computer aided design can be done using 2D (2-dimensional) or 3D (3-dimensional) programs.
2D shows different views of an object. However, these cannot be easily combined or processed into new views. With 3D, the object is visualised in a three-dimensional view. This also allows individual parts to be viewed from different perspectives. To ensure data exchange (standardisation), common exchange formats are used.
In 2D, for example, these are dwg or dxf. In 3D, there are the exchange formats Step, Iges, 3D DXF (wireframe model), 2D DWG (wireframe model) and many more.
Iges and Step are formats for importing and exporting solids (volumes), surfaces and curves. These are the common formats in construction.
STEP (Standard for the Exchange of Product model data) is a standard for describing product data. There are also different formats for saving. We use the format AP 214. The generally accepted file extension for STEP files is .stp.
IGES (Initial Graphics Exchange Specification) is a common exchange format between CAD programs. The generally accepted file extension for IGES files is .igs.