This COMSOL® Multiphysics Programming Reference Manual details features and techniques that help you control COMSOL Multiphysics® using the application programming interface (API) for use with the Java® programming language. The COMSOL API can be used in the Application Builder, in model methods and the Shell window in the COMSOL Desktop®, in a model file for Java, and from the LiveLink™ for MATLAB® interface. If you are using the COMSOL API from the Application Builder, see also the Application Programming Guide for useful information when creating methods for applications.