$2-3 try ebay
A few dollars to a collector- try on Ebay
Postage in 1900 was was 2 cents for a First Class letter in the US. It went up to 3 cents during World War 1 and back down after the war. A postcard could be mailed for 1 cent.
to notify their next of kin. Used to be you could tape money to the postcard or letter and it would be replace with a stamp by the postal people.
several $ hundred try ebay
More or less, it was. End of World War 1, with cutting up of Eastern Europe and the Depression. Pretty much Kicked off World War 2. It is much more involved, but more or less. It is the same war.
expensive
Not much
Of course the value will depend on many variables. A typical postcard should be worth $5 if it was mailed from a soldier overseas. A postcard with a photo may be worth more. Some cards with a commercial Logo such as Coca-cola might have a special interest to collectors. I have a post card mailed from Stalag IIb that has a German stamp and an ink stamp of the prison camp and I would expect it to be worth $25 or as much as $40.
World War II was an event, not a time era.
me
Canada played a much biggger part in World war two
NOTHING. That war was pointless. It cause World War II. It was pretty much every country proving their strength...