Explore the contents of this article with a free Wolfram SystemModeler trial. Today we are proud to announce the release of Wolfram SystemModeler 4. For SystemModeler 4, we have expanded the supported model libraries to cover many new areas. We've also improved workflows for everything from learning the software to developing models to analyzing and deploying them. People have been using SystemModeler in an astonishing variety of areas. Many of those have been well supported by built-in libraries, but many are totally new domains where models typically need to be built from scratch. For most applications, using existing model libraries gives a real boost to productivity, but developing a good library takes a lot of effort. There are many aspects to think of: the best structure for easy modeling, the right level of detail, the interfaces to other components, which components to include, documentation, etc. And you may very well have to refactor the library more than once before you're done. Reusing components and interfaces from already tested and documented libraries not only speeds up development and learning, but also improves quality. So we've made SystemModeler's already broad collection of built-in libraries even larger. For instance, we've added Digital, for digital electronics following the VHDL multivalued logic standard; QuasiStationary, for efficient approximate modeling of large analog circuits; and FundamentalWave, for modeling multiphase electrical machines. There are also many improvements to existing libraries, such as support for thermal ports in the Rotational and Translational mechanics libraries so that heat losses can be captured.