This review is a state-of-the-art summary of current literature on the commercial oenological tannins that are often added to wine. These tannins can come from different origins, which affect their composition and characteristics. The two main sources of oenological tannins are grapes and oak wood. This review describes methods to quantify and characterise oenological tannins and indicates that these methods also need to be improved. These tannins have different interactions with proteins as well as with wine components such as anthocyanins and other phenolics in wine. The suppliers of commercial tannins often emphasise that these products can stabilise colour in red wine and influence the mouthfeel of the wine, among other things. The literature, however, suggests that the addition of these tannins often does not lead to large differences in the chemical profile of the wine and sometimes even leads to unwanted sensory characters being observed in the wine. More research clearly is needed regarding the role of oenological tannins in wine.