The little paper strip with the numbers on it is called the Selo de Garantia, or “Selo” for short. It is issued by the IVDP after they have approved a wine for bottling. This practice begun circa 1941, as the Port Wine Institute was created in 1933. It assures the consumer that the contents of the bottle came from the demarcated Douro region in Portugal. However, it doesn’t speak to the quality of the wine, just the origination of where the grapes came from. In 2018 the law was changed and now instead of the Selo over the top of the bottle, a sticker can be placed on the back label. Both can now be found on bottles of Port wine.