The talk introduces the simulation language Modelica and its concepts for the modeling and simulation of continuous system behavior. The language is competitive to Matlab/Simulink and in addition, supports an objectoriented style of modeling which leads to a high degree of component reuse. System behavior is expressed in an equation oriented style and algebraic and differential equations are directly encoded in the program text based on its modular structure. The talk gives an overview on the language concepts and on the mathematics as the interface to the solvers needed for experimentation, and