Portos are a type of fortified wine that originates from the Douro Valley in Portugal. They are typically sweet and rich, made from a blend of different grape varieties. The fortification process involves adding grape spirit to the wine, which stops fermentation and preserves the natural sugars, resulting in a higher alcohol content. There are several styles of portos, including Ruby, Tawny, and Vintage. Each style has its unique flavor profile and aging process. Ruby ports are known for their vibrant fruit flavors, while Tawny ports are aged in wooden casks, giving them a nutty and caramelized taste.