Waterloo is a city in the Canadian province of Ontario. It is one of three cities in the Regional Municipality of Waterloo (formerly Waterloo County). Waterloo is situated about 94 km (58 mi) west-southwest of Toronto, but it is not considered to be part of the Greater Toronto Area (GTA). Due to the close proximity of the city of Kitchener to Waterloo, the two together are often referred to as "Kitchener–Waterloo", "K-W", or "The Twin Cities".
While several unsuccessful attempts to combine the municipalities of Kitchener and Waterloo have been made, following the 1973 establishment of the Region of Waterloo, less motivation to do so existed, and as a result, Waterloo remains an independent city. At the time of the 2021 census, the population of Waterloo was 121,436.