This course is specifically designed for experts working in the field of electricity markets who want to understand and learn more about a very important function performed by transmission system operators and market players: balancing electricity markets and the involved ancillary services. This function plays a crucial role in ensuring security of supply and has an important effect on the final cost to consumers. Integration of national balancing markets could contribute to enhanced security of supply and to decreasing electricity prices so there is a strong argument for developing cross border balancing markets.