Today's the day we celebrate Queen Victoria's birthday (Victoria Day) in most Canadian provinces. Queen Victoria was actually born on May 24th but the modern holiday is the first Monday before or on May 24th.
Since the death of Queen Victoria, the holiday does double duty as a celebration of the birthday of the current monarch. Queen Elizabeth II was actually born on April 21st—it must be nice to have two birthday parties every year!
Although Queen Elizabeth II is officially Canada's head of state, the duties are actually carried out by her representative, the Governor General. Governors General are appointed every few years and their duties are largely ceremonial. I really like a system where the head of state is not the same person as the head of government. It avoids a lot of problems.
Officially, Canada's form of government is called a Constitutional Monarchy with a Parliamentary System of government.
[The painting of Queen Victoria's Family in 1846 is by Franz Xaver Winterhalter.]