Electronic Travel Authorization (eTA)

An Electronic Travel Authorization (eTA) is an entry requirement for visa-exempt foreign nationals travelling to Canada by air. An eTA is electronically linked to a traveller’s passport. It is valid for up to five years or until the passport expires, whichever comes first. If you get a new passport, you need to get a new eTA. With a valid eTA, you can travel to Canada as often as you want for short stays (normally for up to six months at a time).

Your eTA is linked to the passport you used to apply. You need to present this passport when you check-in to your flight to Canada. If you get a new passport, you need to get a new eTA. The airline staff will scan your passport to confirm that you have a valid eTA. If you do not have one, you won’t be able to board your flight.

[Source] https://www.canada.ca/en/services/immigration-citizenship.html