A point of importance: in many/most jurisdictions, when IRCC asks for "an original", they will also accept a duplicate or extract from the original or official issuing authority. I.e. when they say "original", this does not usually mean that you must find (for example) the original birth certificate issued at birth. You request a copy from the local provincial/national/state/whatever authority (civil registry or whatever the relevant body) and they provide whatever is the standard locally, often issued either on special paper or with stamps. You almost never have to provide the original of e.g. a wedding certificate that was issued at time of your wedding.
Again, I can't say this is identical everywhere, but usually even if the officially-issued document is termed a duplicate or extract or official copy, IRCC will accept as "an original". For the locales where this is not the case, well, that's what the country-specific instructions are for. But even then, "an original" does not necessarily mean "the original."
For clarity the most common official document requests are (in order of "officialness", not what is 'usual'):
-"An original" - meaning issued by an official authority, may be called duplicate or official copy or extract or something else. (If there are cases where the literal original issued at the time of whatever event is required, I don't know about them, but there may be some countries or jurisdictions - check the country-specific requirements).
-Notarised or authenticated copy: a lawyer or notary or some official body certifies it is a true copy of a document they have seen (usually made the copy themselves). Often in combination with official translation (translator certifies).
-Photocopy: obvious.
Note that as far as I'm aware, the official translation approach above usually includes a certified copy and would be required for most/all official documents that are not in English or French.