It depends on whether you mean a picture postcard like one you might send when you are on holiday, or literally, a card that you would send through the post for any purpose, e.g. advertising. Here is a summary of the relevant information from Wikipedia.
First hand painted postcard: 1840, England.
(a hand-painted design on card, posted in London, to himself!)
First printed postcards (advertising): 1848, United States of America
("a picture or blank card stock that held a message sent through the mail, contained printed advertising on it")
First commercial postcards: 1861, United States of America
(created and patented by John P. Charlton of Philadelphia, and manufactured by Hymen Lipman, with no image, and a decorated border.)
First printed "souvenir" post cards with an image: 1870, France
(a souvenir post card from a War training camp. There was no space for stamps, they may not have ever been posted.)
First known picture postcard that was sent in the mail: 1871, Vienna
Hope I helped :)
You use the postage of the country of origin, in this case, you would use Canadian postage.
Yes, you can use a Forever stamp on a postcard, but it's overpaying for postage.
If worried about the size of your postcard, a standard postcard is measured 4 by 6 inches. Postcards can actually be any size so they can be different in any country.
You need to state the country.
Cuba
The first original postcard was first used in Wales (Britan) as an easier job of sending, letters need envelopes, postcards however just needed the stamp.
First, postcard printers must choose good quality paper of the proper thickness; if it's too thin the postcard will get damaged in the mail. Modern postcards are usually printed using the offset printing process, in which the inked image is transferred first to a metal plate and then onto a rubber blanket and finally onto the printing surface.
It depends what country you are in eg. I want to send a postcard to you from Spain. I have to use a Spanish stamp. But you have to use an English stamp to send one to me if you're in England and I'm in Spain.
He made this several times. The first one was pencil on a postcard reproduction.
Sending Postcards with the USPSWhat Is a Postcard?A postcard is a rectangular mailer sent without an envelope.Sending a postcard is an extremely affordable way to communicate when you're using the U.S. Postal Service-regular postcards cost only $0.33 to mail!
Millimeters
To mail a first class international postcard to Canada, you will need to attach $1.10 in postage. The maximum size for a postcard is 6" in length x 4.25" in height.