Scalable Vector Graphics (SVG) is a type of vectorized image format for two-dimensional graphics.
Vector-based formats such as SVG are very useful in technical drawing programs, like FreeCAD, because an SVG image can be scaled to any size without losing its shape or amount of details. The SVG can be scaled to any required resolution and converted to bitmap formats like PNG or JPEG for printing.
The SVG image is described in an XML-type language, which means that it can be opened and edited with a simple text editor to make changes. Due to its text-based nature, the file can also be searched, indexed, and compressed easily. This SVG markup language is an open standard developed by the World Wide Web Consortium (W3C) since 1999. This means that an SVG file should be read and interpreted in the same way by compliant viewers and drawing applications.
How to use
FreeCAD can read and export SVG graphics using the Draft SVG function from the Draft Workbench. SVG files are used for many things, including symbols and icons on the graphical user interface, and for templates. For example, the TechDraw Workbench templates can be created as SVG files with some editable text fields that the user can fill.
FreeCAD is primarily a 3D modelling application, and thus doesn't have many 2D drawing tools, which are mostly included in the Draft and Sketcher Workbenches. To exclusively create 2D shapes, and produce SVG files, there are alternative programs like Inkscape.