Usually found in red wine, tannin is a chemical substance that comes from grape skins, seeds and stems. Tannins are what give wine a dry, bitter taste. Tannins also help prevent oxidation and play a major role in a wine's aging process. A high tannin wine would be a French Bordeaux or any wine produced from grapes such as a Shiraz and Cabernet Sauvignon. Wines such as Pinot Noir and Beaujolais have lighter, thinner skin therefore less tannin. Follow these simple instructions to determine a wine's tannin content.
Take a sip of wine.
Gently swish the wine around in your mouth and at the same time, suck in a little air.
Swallow the wine and exhale.
Notice the drying sensation on your tongue.
If you feel dryness from the tip of the tongue to the back of the throat, the wine is full of tannins.
A low tannin wine will only feel dry on the tip of the tongue.