The first Canadian postage stamps were issued using the British Pound Sterling currency. Canada issued stamps under this currency from 1851 to 1857.
Occasionally, the Canadian Postal Administration would overprint a new monetary value over stamps that were already printed. The result are these surcharged stamps.
The Canadian Postal Administration issued stamps with the base denomination plus an additional value that would be donated to a specific charity or cause.
The PERMANENT stamp is always accepted at the current domestic postage price. If you buy a PERMANENT stamp today, you can use it anytime in the future.
Most of Canada's stamps were issed using the Canadian Dollar currency.