It's a question that is a favorite among wine tasters and the folks pouring behind tasting room bars everywhere. And it's a question that is asked in different ways.
"What do you get from that wine?" or "What do you taste there?"
One answer that is possible would be "tannins." Yes, beyond making red wines good to age or even the healthy properties tannins give to wine, you can "taste" tannins in a wine. Though some people may not realize they are tasting it.
The "taste" of tannins may come across as something like black tea, or char. It manifests itself as a dryness in the mouth, or a sense of needing to pucker. It can taste bitter, but in a way that is positive and lets the taster know they have a strong, big flavor profile to come in a particular wine.
Technically, tannins are polyphenols. That's just a fancy, scientific word for the natural antioxidant compounds that are released from grape skins, seeds and stems when the pressed juice soaks next to those skins. Anyone who has been to a winery and done a tour may have heard the skins referred to as the "cap."
Winemakers talk about punching down the "cap," which refers to the process of pushing the skins (they rise to the top of a vat of juice) down through that juice. In red wines, this process imparts the color but also releases the tannins into the juice. Because the juice for white wines spends little to no time next to their skins, the tannins in white wines are very low.
Ultimately, tannins provide several characteristics to the finished wine.
In the mouth, wine drinkers experience the taste of tannins in several ways. Most commonly, tasters will refer to a big red wine such as cabernet sauvignon or petite syrah as "dry." That drying-out feeling such a wine puts in your mouth is the tannins. Often, that dry feeling manifests as a flavor of strong black tea. But it also can come across as a bit of char, since in addition to polyphenols from the grape skins, those compounds also occur naturally in wood, and most red wines see at least some time in oak barrels that have been toasted.
Beyond just the dry taste, though, tannins work as a natural antioxidant that winemakers love because they protect the wine from spoiling too quickly. Wine consumers have had this characteristic explained to them in terms of a wine being age-worthy. The higher a red wine is in tannins, the longer its ability to age. Being able to age allows a wine to grow and mature into what the winemaker foresees as the ultimate end product. A young wine usually is full of fruit, and can come off as bold. A properly aged wine will taste rich and complex because the flavors and aromas have had the time to blend together as their maker intended.
Of course, health-conscious individuals are acutely aware of the benefits of antioxidants in the body's system. Yet another benefit of tannins.
On the negative side, it is from these tannins that some people suffer tannin headaches. People can test whether they are susceptible to such headaches without drinking wine. The same effect can be found from eating dark chocolate or the aforementioned black tea. Both also are high in tannins.
If a person can drink tea or eat chocolate without getting the same headaches, then those supposed wine headaches are likely not from tannins. More likely, the sufferer simply over-imbibed.