Definition: A wine's pucker power, generally more dominate in younger red wines that haven had the time to soften up with age. Tannins are derived from the skins, stems and seeds of the grapes used to produce the wine. Technically, they are plant-derived polyphenols. Tannins are often described as the component that "dries the mouth" out in red wines. Tannins are largely responsible for giving red wines a defined structure - somewhat like a skeleton provides for body support and movement.
If you wan to identify tannins that are not complicated by the other components in a wine, then brew a very strong cup of tea and take a sip before adding any cream or sugar to soften it up. This drying, astringent compound is a tannin.
