Since March 15, 2016, passengers from visa-exempt countries coming to Canada via air transportation are required, before travelling, to apply online for an electronic Travel Authorization (eTA) to enter Canada.
The eTA costs only $7, and lasts for 5 years or until the passport expiration date, whichever is sooner.
You need to apply through this link. You will need your passport, an e-mail and a credit/debit card to pay the $7 fee.
You will need to fill an online form that should not take more than 5 minutes. You will have to answer basic questions about yourself (name, address, profession, criminal history if any, …), about your intended stay in Canada (when and where are you going in Canada) and your passport information (number, date of expiration, …).
You should be careful when entering your passport number as you can be refused boarding if there’s a mismatch.
The eTA is valid for five years, or until the passport expiration date, whichever is sooner.
Your eTA will usually be granted within minutes of filling and validating the online eTA form. However, some requests could take several days to process if you’re asked to submit supporting documents (case of a Brazilian citizen holding a US visitor visa for example). It is best to get an eTA before you book your flight to Canada.
To find out if your eTA is still valid, you can submit a web enquiry form and select ‘Electronic Travel Authorization’ and ‘Case-specific’ inquiry. If your eTA has expired, you will need to apply for a new one to be permitted entry in Canada.