Tawny ports are wines made from red grapes that are aged in wooden barrels, exposing them to gradual oxidation and evaporation. As a result, they gradually mellow to a golden-brown colour. The exposure to wood imparts "nutty" flavours to the wine, which is blended to match the house style.

Tawny Reserve port (without an indication of age) is a basic blend of wood aged port that has spent at least seven years in barrels.

Tawny with an indication of age is a blend of several vintages, with the average years "in wood" stated on the label, the official categories being 10, 20, 30 and over 40 years. For each category, the average age of the various vintage is at least that of the given category.

The cheapest forms of Tawny Port are young wines made from a blend of red and white grapes. Unlike Tawny Reserve and Tawnies with an indication of age, they may have spent little or no time maturing in wood.

Tawny ports from a single vintage are called Colheitas (pronounced col-YATE-ah, meaning harvest). Instead of an indication of age (10, 20...) their actual vintage year is mentioned. However, they should not be mistaken with Vintage Port.