A file with .igs (Initial Graphics Exchange) extension is a 2D-3D design exchange file format that is independent of source or destination file format specifications used by CAD applications. It is used to exchange design information about circuit diagrams, wireframes, the freeform surfaces between two independent systems. IGS files can be opened by applications such as Autodesk, FreeCAD, CADEX CAD Exchanger, and other similar applications.
SVG files are Scalable Vector Graphics Files that use XML based text format for describing the appearance of image. The word Scalable refers to the fact that the SVG can be scaled to different sizes without losing any quality. Text based description of such files make them independent of resolution. It is one of the mostly used format for building website and print graphics in order to achieve scalability.
You can also convert IGS into many other file formats. Please see the complete list below.