Unlike most countries, but paralleling its counterpart, the United States, football in Canada refers to the gridiron-based game developed in both countries over the course of the late 19th and early 20th centuries, and not to association football (which is known in Canada as soccer).
The CFL operates a two-week preseason beginning in May, an 18-game regular season from June to October, and a six-team playoff tournament, culminating in the Grey Cup on the third Sunday of November.
Until 2017, they were the only professional indoor American football team to have attempted to take root in Canada; a second attempt, the Niagara Spartans (run by the established semi-pro Steel City Patriots team in the Hamilton area), played in the Can-Am Indoor Football League; the Spartans had their season cut short after four games, all on the road, when international border issues with the league's American teams proved to be unworkable.
The NFL has occasionally played games in Toronto (as well as, more sporadically, other Canadian cities) over the course of its history but has never attempted to permanently place a team there.
The Bills Toronto Series was the NFL's most direct presence in Canada; in that series, which ran from 2008 to 2013, the Buffalo Bills played one of their regular season home games in Toronto's Rogers Centre.