Visa-exempt foreign nationals are not required to have an eTA (electronic travel authorisation) before November 9, 2016.  The leniency period has been extended from September 29, 2016.  Here is an information link.

An eTA, once in effect, is an Electronic Travel Authorisation that will signal airline staff and crew that you have been authorised by Canada to board your plane to come to Canada. It is not a visa which you might need if you were not visa-exempt.

Watch for online travel agents that are charging an inflated fee to apply for an eTA on your behalf. An eTA may be purchased for $7 from the official Canadian Immigration and Citizenship (cic.gc.ca) website, linked here.

Allow plenty of time to purchase your eTA. As of today, there are still problems occurring in the process used by Citizenship and Immigration Canada. Some travellers are receiving their eTA immediately, but some are finding it takes 2-4 months for the process to complete, especially if you receive an email saying  that your application will take 72 hours. These "few hours" are not happening as some posters are saying that the "second look" process took several months.  In the intervening time, they are left in limbo.

Anyone who would like to send feedback of your application experience to Citizenship and Immigration Canada may do so with this email:

The Hon. John McCallum, MP

Ottawa

minister@cic.gc.ca