What terroir means and where it stops.

The usual answer to "what is terroir?" is soil, along with a picture of the soil flavouring the wine. The first part is too narrow and the second is mostly wrong. Terroir is the whole natural setting of a vineyard: soil and subsoil, drainage, slope and aspect, altitude, climate and microclimate. It also takes in the human practices that grew up with the place, from the grapes planted to the way they are pruned and the day they are picked.

Understood that way, terroir is real and you can taste it. It explains why two vineyards a short walk apart can make recognisably different wines, year after year. It also has limits and the word is regularly used well beyond them.

What is terroir, factor by factor

The International Organisation of Vine and Wine, the intergovernmental body for the sector, adopted a formal definition in 2010. It describes an area where shared knowledge of how the natural environment and vineyard practices interact develops over time, giving its wines distinctive characteristics. In short, a place and the people who have learned what it does.

• Soil and subsoil. What the roots grow through. Its effects run mainly through water, nitrogen and warmth rather than through any direct flavour.
• Drainage. Gravel and stony ground shed rain quickly; clay holds it. A vine kept a little short of water stops growing shoots sooner and makes smaller berries with more colour in their skins, which for red wine usually means better grapes.
• Slope and aspect. How steep the vineyard is and which way it faces decide how much sun it catches, how fast rain runs off and where cold air drains on a still night.
• Altitude. Higher vineyards are cooler, especially at night, which slows ripening and helps the grapes keep their acidity.
• Climate and microclimate. The region sets the broad pattern of sun, rain and warmth. The microclimate is the local twist: a sheltered fold in the hill, a river that softens frost, a gap that funnels cool wind.
• People. Which grapes, how densely planted, how pruned, when picked. Over generations these choices settled on what suited each place, which is why they belong in the definition.

Research keeps returning to water and nitrogen. One detailed study followed three soils and three grape varieties through five vintages. The weather of each year shaped the grapes' composition most, above all their acidity, while soil had the bigger say over their colour. Both worked largely through the water and nitrogen the vines received.

The fine contour lines drawn across this site are a quiet nod to the idea. A contour map shows slope, height and shape, which govern how sun, water and cold air move across a hillside. It says nothing about flavour. That part you have to taste.

Burgundy's climats: the purest case

Burgundy took the idea further than anywhere else. Along some 50 kilometres of hillside south of Dijon, the vineyards are divided into named plots called climats, each with its own boundaries and history. There are 1,247 of them on the Côte de Nuits and Côte de Beaune. In 2015 UNESCO inscribed the climats of Burgundy as World Heritage.

The system grew out of observation. From the Middle Ages, monastic orders and the Dukes of Burgundy tied each wine ever more closely to the plot it came from. Many of the boundaries are still marked on the ground by paths and stone walls. The appellation decrees of the 1930s made them official.

Burgundy therefore classifies land: its four levels follow the vineyard, whoever farms it. Bordeaux works the other way. Its 1855 classification ranks châteaux and an estate keeps its rank even as its vineyards grow, shrink or change hands.

Two things make Burgundy the clearest test of the idea. The Côte grows essentially one red grape and one white, Pinot Noir and Chardonnay, so the variety is held constant. And many growers make wine from several plots, so the cellar is held constant too.

The principle is not only European. Wuyi rock oolong, from the mountains of northern Fujian, is prized for the rocky slopes where it grows, while most of the Wuyi tea on the market is a commercial grade from lower ground.

How to taste terroir yourself

You do not need a map, only the right comparison. Change one thing and hold everything else still: same producer, same vintage, two neighbouring plots, side by side. Same hands in the cellar, same weather, same grape. What is left is the place.

Pairs that are easy to find:

• Village and premier cru. Two wines from the same Burgundy grower, vintage and village.
• Two Barolo vineyards. Barolo allows official vineyard names on its labels and many producers bottle several sites separately. More in our guide to Barolo and Barbaresco.
• Two German Rieslings. One estate, one vintage, two named vineyards.

Taste them side by side, blind if someone else will pour. Look at shape and texture before flavour: which wine feels broader and which tighter, where the acidity sits, whether the tannin is fine or firm, which one lasts longer. Aromas shift from minute to minute in the glass; the feel of a wine is steadier and usually the better clue.

The same comparison makes one of the best evenings among our themes for a blind tasting: pour the neighbours blind and see who can tell which is which.

Where the idea stops

Terroir is real. It is also asked to carry more than it can.

• Winemaking can drown it out. Very late picking, heavy extraction and plenty of new oak can make wines from different places taste alike. Site shows most clearly when the cellar is restrained.
• Vintage can dominate. A very hot or very wet year can leave a stronger mark on the wine than the site does. See when the vintage matters most.
• Minerality is a real sensation with a disputed explanation. Tasters use the word freely but define it in very different ways, though in studies it tends to go with wines that are fresh, high in acidity and light on fruit and sweetness. What does not hold up is the idea that you are tasting the rock. The minerals in wine are nutrients only distantly related to the vineyard's geology, present in minute amounts and generally tasteless. The sensation seems to come instead from acidity, from compounds formed during fermentation and from the absence of obvious fruit.
• Marketing uses the word loosely. "Terroir-driven" on a back label means little unless the label also says where. A wine blended from across a whole region can be delicious and good value; what it cannot be is a portrait of one place.

Using terroir when you buy

Treat terroir as a claim to test. When a label names a specific vineyard or village, the producer is inviting comparison, so take them up on it. When a label only uses the word, look for the name of a place and a grower you trust.

Follow good producers across their sites instead of chasing famous vineyard names from anyone.

A great grower's village wine often says more about its place than a careless producer's grand cru.

Before you spend on the idea, try it: two neighbours from one grower and one vintage, opened together, will show you in an evening how far it goes. A blind tasting is the fairest way to run the comparison.