Wine writing is full of fruit. Blackcurrant, gooseberry, wet stone, tobacco leaf. Those descriptions are real, but they are the last thing to learn, not the first, because they depend on a vocabulary of smells most people have not deliberately built. The structure of a wine is easier, more useful, and something your mouth already knows how to measure.
There are six components. Learn to notice them and you can describe any wine well enough to buy the next one on purpose.
1. Sweetness
Sweetness is sugar left over after fermentation. Yeast converts sugar to alcohol; if it finishes the job, the wine is dry, and if it is stopped or runs out of steam, the wine is sweet. Most wine sold today is dry.
The confusion is that ripe fruit flavour reads as sweetness even when there is no sugar. A warm-climate Californian red at 15 percent can taste sweet and be technically bone dry. Test it by attention: sweetness coats the front of the tongue and lingers. Fruitiness is a smell.
2. Acidity
Acidity is what makes your mouth water. It is the single most important quality in wine and the one beginners notice last. It comes from the grape, and grapes lose acid as they ripen, so cool regions and early picking give high acid and hot regions give low acid.
High acidity makes a wine feel fresh, keeps it alive with food, and lets it age. Low acidity makes a wine feel soft, round and, at the extreme, flabby. If a wine tastes tiring after two glasses, low acidity is usually why.
3. Tannin
Tannin comes from grape skins, pips and stems, and from oak barrels. It is not a flavour: it is a texture. It dries the inside of your cheeks and the front of your gums, the same feeling as over-brewed black tea.
Only red wines have significant tannin, because only reds are fermented in contact with their skins. Thick-skinned grapes such as cabernet sauvignon and nebbiolo give a lot; thin-skinned grapes such as pinot noir and gamay give little. Tannin softens over years in bottle, which is most of what people mean when they say a wine needs time.
4. Body
Body is how heavy the wine feels, and it tracks alcohol more than anything else. The familiar comparison is skimmed milk, whole milk and cream. A Mosel riesling at 8 percent is light. A Barossa shiraz at 15 percent is full.
Body is not quality. Light wines are not lesser wines. Much of the best wine in the world is light, and the assumption that heavier means better is the single most expensive mistake a new buyer makes.
5. Alcohol
Alcohol carries body, sweetness of impression and warmth. You feel it as heat at the back of the throat after you swallow. Anything at or above 14.5 percent will show it clearly.
It is printed on every bottle, so it is the one structural component you can check before buying. Use it.
6. Oak
Oak is not an ingredient of grapes. It is a container, and it adds vanilla, coconut, clove, smoke, toast and sometimes dill, depending on where the tree grew and how the barrel was charred. New barrels give a lot; old barrels give almost none and act simply as a vessel that lets a little oxygen through.
Oak is the easiest component to over-apply and the one most often used to make a thin wine seem substantial. If a white wine tastes of butter and vanilla and not much else, that is oak and malolactic fermentation doing the work the fruit should be doing.
How to practise
Open two bottles at once. That is the whole method. A single wine tells you very little because you have nothing to measure it against, and two wines side by side make every difference obvious.
Good first pairs: a Marlborough sauvignon blanc against a Sancerre, which isolates ripeness in one grape. A Beaujolais against a Barossa shiraz, which isolates body and tannin. An unoaked Chablis against an oaked Californian chardonnay, which isolates oak. Write one sentence about each. Within a dozen pairs you will have a working palate.