TSO — what is a transmission system operator?
In depth
TSOs are typically state-owned or strictly regulated monopolies because running the grid is a natural monopoly — you can't have two competing high-voltage networks in the same country.
Their core jobs: keeping frequency at exactly 50.00 Hz (any deviation risks blackouts), publishing the day-ahead clearing prices, settling cross-border imbalances with neighbouring TSOs, and planning multi-decade grid expansions like new HVDC undersea cables.
For consumers, the TSO is invisible — your supplier handles the bill. But every euro on your electricity invoice ultimately flows through your country's TSO.