Alcohol is the most obvious component of wine — but the hardest to talk about. We’re all familiar with its effects on us, both good and bad, but we’re much less conscious of how alcohol influences the way a wine tastes and feels in our mouth. In some ways, alcohol fills the same role in wine that fat does in cooking: not only does it add softness and weight, but it also helps to carry the flavors and makes the beverage more palatable. It’s like that final pat of butter of dash of olive oil that makes whatever you’re cooking that much more delicious.

Alcohol adds weight and viscosity to a wine. In general, higher alcohol wines will feel fuller and rounder in your mouth. Even if you had no sense of smell or taste, you could register the difference between a wine with 12.5% alcohol (imagine a Cabernet Franc-based red wine from the Loire Valley, like a Saumur-Champigny) and a wine with 15% alcohol (a Zinfandel from Sonoma, for example) — just like you could tell the difference between a glass of skim milk and a cup of cream.

But for wine, as for people, there’s a fine line between the right amount of alcohol and too much, and once you cross it, watch out. At higher levels, alcohol will  register on your palate as a cloying sweetness that clashes with food. Too much alcohol can also  create an unpleasant burning sensation in the back of your throat. Wine people will say that a wine is “hot” when this happens, and they don’t mean it as a compliment. Alcohol shouldn’t be the first thing you notice when take a whiff or a sip. It should play nice with all the other elements in the wine — the acidity, the tannins, and any residual sugar that may be present — and help amplify the aromas and flavors.

Alcohol is a subject of much debate in the wine world, as alcohol levels have been creeping up in recent years. Blame America, if you must (everyone else does.) It’s both nature and nurture: the hot, sunny climate you find in many of California’s wine producing regions translates into grapes that are high in sugar, and more sugar translates into higher alcohol. (Remember: fermentation is sugar + yeast turning into alcohol + carbon dioxide.) Global warming also plays a part: temperatures are on the rise, and so too are alcohol levels. Climate change deniers need only look at the fact that England is now producing red wines for the first time since the unusually balmy Medieval period to reconsider their stance.

The nurture part is more complicated, and more divisive. Our American appetite for sweetness and overall in-your-faceness vs. the more subtle tastes of our European cousins has prompted the wine industry to push for riper grapes, bigger flavors, and more alcohol. Some of these wines can be thrilling, or, at the very least, a lot of fun. Too many of them, however, grab you by the throat and make you beg for mercy. They’re positively boozy, with an alcoholic kick that overshadows the wine’s other virtues (or, to take the cynical view, hides its flaws) and makes it impossible to match with food.

Fortunately, alcohol is one of the easiest things to decipher, as it must be clearly marked on all wine labels. At the low end of the alcohol range, sweet German wines can clock in around 8% or 9% alcohol by volume. On the high end you have Port, which usually comes in around 20%. Most of the dry wines we drink live in the 12-15% range. In terms of matching with food, bigger alcohol wines are better with heartier dishes, while lower alcohol wines work with lighter fare. And when in doubt, better to err on the side of too little alcohol than too much. Trust me on this one.