A valid passport is in general required for entry into Canada. Different entry requirements apply for Canadian citizens and permanent residents, U.S. citizens and permanent residents, and other international visitors.
For further information on travel documents, see here: http://www.cbsa-asfc.gc.ca/travel-voyage/td-dv-eng.html
All travellers must be identified on a Canada Border Services Agency (CBSA) Declaration Card made available during travel.
Visa requirements and visa exemptions
Citizens of certain countries and territories need a visa to visit or transit Canada. Others will need an Electronic Travel Authorization (eTA).
For further information on visa requirements and visa exemptions, see here: http://www.cic.gc.ca/english/visit/visas-all.asp
Electronic Travel Authorizations (eTA)
Canada is introducing a entry requirement, known as an Electronic Travel Authorization (eTA), for visa-exempt foreign nationals (see above) travelling to or transiting through Canada by air. Exceptions include U.S. citizens and travellers with a valid visa.
Starting August 1, 2015, eligible travellers can apply online for an eTA. On September 29, 2016, this new requirement will become mandatory and travellers will need an eTA before they can board their flight to Canada. To find out more, visit Canada.ca/eTA