H-infinity methods are a set of mathematical techniques used in control theory to design systems that can maintain performance despite uncertainties. These methods focus on minimizing the worst-case scenario of system output, ensuring stability and robustness against disturbances and model inaccuracies. In control systems, H-infinity techniques help engineers create controllers that optimize performance while handling variations in system dynamics. By formulating problems in terms of linear matrix inequalities, these methods provide a systematic approach to achieve desired specifications, making them valuable in various applications, including aerospace and automotive engineering.