What is a standard parts library?

When you use a CAD software to create a design, this design consists usually of two different types of components: Custom parts that are specific to your purposes and have to be custom made (e.g. by 3D printing), and standard parts like nuts and bolts that you can buy in a hardware store.

A standard parts library relieves you from the tedious task of modeling standard parts by providing them readily usable, so that you can focus on the interesting aspects of your design.

While many commercial vendors offer standard parts libraries with their tools or for a fee, there is no free (as in freedom) standard parts library, yet. BOLTS tries to fill this gap.