Summary:  Polyphenols, in particular anthocyanins and tannins, are the main contributors to wine color and mouthfeel, and are strongly related to the wine quality evaluation. In this WSG Live, an introduction to tannin's origin in grapes, evolution during ripening and extraction in the winemaking process will be explained. Moreover, the implication of the technological approach to vinification will be discussed, such as maceration style or the use of oak containers.