Safety and the law
What are the legal aspects of gambling in Canada?
Gambling is legal in Canada and regulated province by province. The Criminal Code allows provinces to conduct and manage it, which is why the rules change when you cross a border.
For a recreational player, winnings are generally not taxable income in Canada. That changes if gambling is your business.
Age and province
Eighteen in Alberta, Manitoba and Quebec. Nineteen everywhere else. Operators check this at registration and enforce it at verification.
Ontario is the only province with an open registered market for private operators. Everywhere else the provincial corporation runs the legal domestic product, and international sites operate under offshore licences.
Tax
Casual gambling winnings are not treated as income for most people, on the reasoning that losses are not deductible either. Interest earned on winnings is taxable in the normal way.
Somebody gambling professionally, with system, expectation and business-like conduct, can be assessed differently. That is a conversation with an accountant, not with a comparison site, and nothing here is tax advice.
Offshore operators
It is not an offence for an individual in Canada to play at an international site. The legal exposure, such as it is, sits with the operator rather than the player.
The practical exposure sits with you though. An offshore dispute is handled by an offshore regulator, and that is a much longer road than a complaint inside a provincial system. Our province pages list which apps sit on which side of that line, one province at a time.