Ontario is located in the east-central part of the Canada, the largest by population and second largest (after Quebec) in total area and is also the only Canadian Province that borders the Great Lakes.

The capital of Ontario is Toronto, the largest city in Canada. Ottawa, the capital of Canada, is located in Ontario as well. The 2006 Census counted 12,160,282 residents in Ontario, which accounted for 38.5% of the national population.

Ontario continues to be the province of choice for more than half (52.3%) of the 1.1 million new Canadian immigrants. This was down slightly from the 55.9% of new Canadian immigrants who settled in Ontario between 1996 and 2001. The Canada 2006 Census enumerated 3,398,700 Canadian immigrants in Ontario. They represented 28.3% of the province's population, the highest proportion of all 10 provinces and the highest in Ontario's history. Most Canadian immigrants that settled in Ontario live in the census metropolitan area of Toronto (68.3%).

Ontario's rivers, including its share of the Niagara River, make it rich in hydroelectric energy. Since the privatization of Ontario Hydro which began in 1999, Ontario Power Generation runs 85% of electricity generated in the province, of which 41% is nuclear, 30% is hydroelectric and 29% is fossil fuel derived. OPG is not however responsible for the transmission of power, which is under the control of Hydro One. Despite its diverse range of power options, problems related to increasing consumption, lack of energy efficiency and aging nuclear reactors, Ontario has been forced in recent years to purchase power from its neighbours, Quebec and Michigan to supplement its power needs during peak consumption periods.