If you were given a visitor record, student or work permit, the expiry date is marked on the document.

If you leave Canada during your authorized stay, you must get a new visitor visa to re-enter Canada.

There are two exceptions: you can visit the United States or Saint-Pierre et Miquelon and return to Canada without getting a new visa, as long as you:

•return within the initial period authorized by the immigration officer or
•have a valid visitor record, work permit, study permit, or a temporary resident permit (authorizing re-entry) and return within the initial period authorized by the officer.