The word “tannin” comes from the French term for the acids extracted from oak bark used to convert animal skins to leather. If you’re not sure what tannins taste like, take a tea bag (black tea, not herbal or flavored), place it in a cup and add freshly boiled water. Leave the tea bag in the water for fifteen minutes without adding sugar or milk. Once the fifteen minutes have passed, have a drink: that bitter taste is tannin.
In wine, tannins exist naturally in the skins, seeds and stems of grapes. They are also obtained by aging the wine in oak barrels. Tannins are mainly found in red wines but they do occur in white wines that are barrel aged.
Tannins give the wine its backbone. They also help in extracting color from the grape skins and stabilize them so they don’t fade over time –essential for red wines. Wines with little tannin should be enjoyed young while wines with a lot of tannins require aging, allowing the wine to mature and impart maximum fruit flavors.