Parchment is what people used to write on before paper was common, hundreds of years ago. Instead of being made from trees, parchment was made from animal skins.
As early as the second century BC, ancient Greeks invented a method of treating animal skins to make a writing surface, parchment, that was less expensive than the papyrus they used before that. Parchment continued to be used through the 1400s, when Europeans began making paper. These days, you're most likely to see parchment in a museum or historical movie. The word comes from the name of the city where it was invented, Pergamon.