It depends on the country in which you live. In the US stamps never expire, so the answer is yes. ( There are a few old exceptions, but you are not likely to have any of these lying around. Also special delivery stamps which did not really pay for postage, but for a service that is no longer available, are not valid for anything anymore.)
USPS accepts all unused U.S postage stamps since 1861, these stamps are still valid and are valued at whatever price they state, however if no value is shown the the value depends on the particular stamp.
All stamps issued by the government since 1861 are still valid for postage.
In the US, they are still valid for postage at their face value. The US has never de-valued their postage stamps. For a collector's value, you would have to consult a catalog to identify and value the stamp. Look for one at your library or on line.
Certainly, they are still valid for postage. You just have to use enough of them to equal the current postage rate for the envelope or package you are mailing.
It is still valid for postage. The G make up rate is worth 3 cents toward current postage.
The F series stamps were issued in 1991. The postage stamp has a face value of 29 cents.
The is a recent stamp with little collector's value. If unused, it is still valid for postage at 37 cents. If used, it wholesales for about 50 cents per hundred.
If the stamp has not been devalued by the country of issue, yes, for postage in that country. It is only going to be worth face value which could be a fraction of its actual value in a few cases.
Oh, of course, friend! If you're referring to the H Rate Makeup stamp for your letters, don't you worry. As long as you have them, you can still use them to send your mail with a little extra love. Keep spreading joy with your letters, just like painting happy little trees.
It is still valid for postage. The exact face value will have to be found on the USPS web site.
They are no longer being sold by the post office. They are still valid for 15 cents worth of postage.
Yes, the stamp is still valid for postage in the US. Just equal or exceed the cost of mailing the item.