Elia is Belgium’s transmission system operator and is responsible for the transmission of electricity. Electricity is transmitted over the high-voltage grid from electricity generators to the distribution system operators and large industrial consumers. As system operator, Elia organises transparent, objective and non-discriminatory access to the grid. Elia owns all of Belgium's 150 to 380 kV grid infrastructure and almost 94% of its 30 to 70 kV grid infrastructure.

Elia's grid forms a key connection between France, Europe's largest electricity exporter, and the markets of Northern Europe.

Elia's main activities are:
- transmission operator: maintaining and developing grid infrastructure and connecting electrical installations to the grid;
- system operator: providing smooth, objective and transparent access to the grid, supplying all services to enable the transmission of electricity, monitoring electricity flows on the grid to ensure effective operation and constantly managing the balance between electricity consumption and generation;
- market facilitator: taking initiatives to improve the operation of the electricity market.