Stamps are what keep the postal system going. Post a letter, a check, or a card, and all you need are an envelope and a stamp.
When we were younger, I and my younger brother collected stamps. We had a special album for displaying those stamps. Those were the days when people wrote letters as a routine and not just for special occasions. We would immediately demand the stamp if it was one we didn’t have in our collection. We especially valued the overseas mail. Then on special occasions, we were allowed to purchase sets of stamps. I don’t remember exactly, but a packet of stamps could be purchased from stationery shops. They had all sorts of stamps.
I don’t remember what happened to all those albums when both of us outgrew our hobby. Perhaps they were donated or (gasp) thrown away.
For visually challenged writers, the image shows a colourful collection of used stamps from various envelopes and postages.