What is a VISA?
A visa is an official document, usually stamped or glued inside a passport, giving permission from a foreign authority for you to enter a country. Some countries (ie. Australia) use an Electronic Travel Authorization (ETA) - which is a VISA that has be electronically linked to your passport.
Requirements, fees and processing times vary, depending on the country and type of visa you need. The most common categories are business, work, student and tourist visas. Before your departure, consult the Country travel advice and advisories for destination-specific visa information. You will almost certainly need a visa if you plan to remain in a foreign country for a longer period (usually more than 90 days).
Some countries will issue a visa upon your arrival, but it is not a common procedure. Visas must be obtained before leaving Canada. You may be denied entry if you do not have a visa when you arrive in a country that requires one.
You are responsible for ensuring that your passport contains empty visa pages. If the pages of your passport have become filled with visas or entry and exit stamps, be sure to apply for a new passport.
To extend your stay in a country beyond the period permitted by the visa you currently hold, or to change the status of your visa (for example, from a tourist visa to a work visa), contact the nearest Canadian government office abroad and consular officials will refer you to the proper authorities in that country