Four examples for active processes at interfaces are studied and reveal complex pattern formation phenomena including complex defect dynamics, standing waves and turbulence, bistability and domain formation and Turing patterns. The examples studied range from active Langmuir monolayers to thin films with floating molecular machines and biomembranes with active proteins. It is shown that linear stability analysis and numerical simulations of the resulting continuum model equations allow to qualitatively reproduce previous experimental observation in some cases and offer intriguing predictions for future investigations in the laboratory.
