The Greater Toronto Area (locally abbreviated as the GTA) is the most populous metropolitan area in Canada. The GTA is a provincial planning area with a population of 5,555,912 at the 2006 Canadian Census. Total population and land area of the City of Toronto and the regional municipalities of Durhambut excluding Whitby, Halton, Peel and York which form the Greater Toronto Area, however many towns within those regions, such as Whitby, are not considered part of the GTA. Population and land area figures for Toronto and the regional municipalities come from the 2006 Canadian census: blank">http://www12.statcan.ca/english/census06/data/popdwell/Table.cfm?T=702&PR=35&SR=1&S=3&O=D. The Toronto _Census Metropolitan Area defined by Statistics Canada is smaller than the GTA planning area and had a population of 5,113,149 at the same 2006 census.

The Greater Toronto Area is the 6th largest metropolitan area in North America. In addition to the City of Toronto, it includes the Regional Municipalities of York, Halton, Peel and Durham. The term GTA only came into usage in the mid-1990s after it was used in a widely discussed report on municipal governance restructuring in the region.