Ontario Power Generation: Generates 60 per cent of Ontario’s electricity.

Hydro One: Operates 97 per cent of Ontario’s transmission network.

Independent Electricity System Operator: Ensures reliability, forecasts short-term demand and supply, monitors supply, and manages the Ontario wholesale market.

Ontario Power Authority: Responsible for system planning (generation, transmission, demand and conservation), contracts for new generation and conservation, and manages contracts for about 40 per cent of Ontario’s generation.

Ontario Energy Board: Independent, quasi-judicial regulator of Ontario’s energy sector.

Licensed Transmission System Operators: Transmit electricity (There are five; Hydro One Networks is the largest).

Local Distribution Companies: More than 80, mostly owned by municipalities, deliver electricity and serve customers in a given area.

Electricity Retailers: Seventy-seven private-sector companies that sell contracts to businesses and consumers

Privately-owned generators: Facilities that produce energy (Bruce Power, wind and solar energy companies)