For domestic flights all adults are required to have one current piece of Canadian government-issued photo ID, or two pieces of Canadian government issued non-photo ID. All infants and children aged 17 or under must be able to provide proof of age. We strongly recommend that all children travel with one piece of government-issued identification. More info.
For international travel, adults, children and infants require a valid passport. Travellers of all ages require identification that matches the name and spelling on their ticket. You are responsible for making sure that you, and any child/infant travelling with you, have the proper identification and travel documentation required to enter or connect through each country on your itinerary. Please consult with the nearest embassy or consulate of each country you plan to visit. A valid (not expired) Nexus card will be accepted for travel to/from the US only, however a valid passport is still required.
If you have no Canadian government-issued photo ID for a domestic flight you can use a passport, Nexus card, US permanent resident card or US enhanced driver's license, or international travel document like Laissez-Passer.