COMSOL 5.1 is a major upgrade that delivers new and enhanced functionality across all products, including COMSOL Multiphysics and the Application Builder and COMSOL Server, as well as the add-on modules. Among the significant updates are enhancements to numerous core modeling and simulation capabilities and an improved user experience for application design. Additional features include 20 demo apps showcasing the Application Builder, including email with simulation reports; full access to the entire library of models and applications with any license; ready-to-use part libraries for fast geometry creation, and tools for building part libraries; tighter integration between the Model Builder and Application Builder; and the ability to distribute computations and serve more users by running applications on multiple computers using COMSOL Server.