Simply put, it is the transformation of a project from a CAD environment into a BIM environment. That is, the transfer of a construction project from simple lines or blocks to a full-fledged 3D model with a diverse range of information, from size to material and other physical properties.
Since today the world has not yet completely switched to BIM technology and is declining in the process of transition, so there is still a need to convert one format to another. This is due to several reasons, one of which is simplified and therefore faster work on the project in CAD programs.