The European Network of Transmission System Operators for Electricity (ENTSO-E) is an association representing 40 electricity transmission system operators (TSOs) from 36 countries across Europe, thus extending beyond EU borders. It manages the Continental Europe Synchronous Area (CESA). ENTSO-E was established and given legal mandates by the EU's Third Package for the Internal energy market in 2009, which aims at further liberalising the gas and electricity markets in the EU. Ukrainian Ukrenergo became the 40th member of the association on 1 January 2024.