Why is it called port wine?

Port, often known as Porto, is a delightful, fortified, typically red wine from the Douro area of northern Portugal, titled after the town of Oporto, where it is matured and packaged; it can also refer to any of numerous fortified wines created in other countries. Port comes in a variety of colors, such as red, white, rosé, and an older version called Tawny Port.