That is what stamps are for, to pay postage. In the US you buy postage stamps and put them on mail to any other country in the world.
No, that is not valid for postage. It was just easier to print them that way. Make sure you use a real postage stamp on your letters.
How possible it is. For Collection, one can use US postal stamps. But for regular use for letters or parcels not possible. Bulgaria is not a state of USA
Yes, you can use a global US forever stamp to send a letter within the United States. The global forever stamp is designed for international mail, but it can also be used for domestic letters since it covers the cost of sending mail regardless of the destination. However, it's usually better to use a regular forever stamp for domestic mail, as it is specifically intended for that purpose.
The stamp has to be accepted where you mail the letter. If you are mailing in Canada, you need a Canadian stamp. If you are in the US mailing to Canada, you can use a US stamp.
From the US the cost is 98 cents in 2010. You can buy a 98 -cent stamp or can use any combination of stamps that total 98 cents or more.
It depends on the weight of the package or envelope. Letters weighing one ounce or less require a 49 cent stamp called a "forever" stamp.
You can use US postage since origin US but since int'l will take more than 1 stamp
Yes, you can ... forever ...
No, you should only use US stamps for mail posted in the US.
Yes, the 2015 additional ounce US stamp can be used as a Forever stamp. While it was originally intended to cover the cost of additional ounces for letters, it retains its value and can be used for standard first-class mail, regardless of current postage rates. However, it is advisable to check current postage rates to ensure it meets the required amount for mailing.
Postage for ordinary first-class letters was 2 cents in 1928.
The current rate is 44 cents for standard First Class Mail.