I have a vivid recollection, from when I was just starting out in the wine trade, of meeting a certain wine producer in the rural depths of southern France.

We tasted his stunning wine straight from the barrel, pausing in silence to savour all its mesmerising intricacies. But then I ruined the moment by asking him which grape varieties the wine was made up of, and in what proportion.

“I don’t give out technical information,” he harrumphed. “It means nothing. The best wine is, frankly, indefinable.”

While this classic Gallic perspective holds an undeniable charm and logic, the issue of grape varieties is very important to the modern wine drinker. Wine is surely the most evocative of foodstuffs in terms of expressing its origins, and one key factor in determining how a wine will taste is the grape variety from which it is made.

There are thousands of varieties of Vitis vinifera, the European wine-giving vine, a direct result of this tenacious plant’s penchant for mutation. However, there are a much smaller number of major grape varieties used to make wine, the result of centuries of trial and error, as well as the demands of the market.

The most widely planted grape variety for red wine is Cabernet Sauvignon. Its home from home is Bordeaux but it has become so popular in recent years that it can be found in virtually every red-wine growing area of the New World. Relatively easy to grow and crop, it tends to make cassis-scented wines with fresh acidity and tannin. It often crops up in red blends (Bordeaux essentially being a region of blended wines) because its firm structure works well in conjunction with fleshier, softer varieties.

One of Cabernet’s most common blending partners is Merlot, the world’s second most planted red variety and whose soft, plummy nature is ideal for the purpose. Its easy-going appeal has, however, also been its undoing – producers have tended to plant it anywhere and everywhere, when in fact it needs specific conditions to work well. The resulting raft of boring Merlots has inevitably led to its reputation taking a knock, though it’s worth remembering that one of the wine world’s most highly prized and expensive reds is Château Pétrus, made in Pomerol, Bordeaux, almost exclusively from Merlot.

Chardonnay is another variety that, like Merlot, has suffered from over exposure. Because it is easy to manage in a range of conditions it was enthusiastically adopted by New World countries like the USA and Australia, in the process becoming the world’s most planted fine white grape variety. Wines made from Chardonnay tend to reflect their origins; thus Chablis is steely and crisp, while many Australian versions are warm and ripe. Its natural affinity with oak has been both a blessing and a curse – great care is needed to avoid the wine becoming sickly, but when the process is managed well (as in the best white Burgundy) then it can make some of the finest white wines in the world.

Something of a direct contrast to Chardonnay, Sauvignon Blanc makes an aromatic, tangy and usually unoaked white wine. Perhaps its most vibrant expression can be found in New Zealand, though other countries like Chile and South Africa are also making exciting, expressive Sauvignon. Striking aromas of green pepper, passion fruit and citrus are what identifies these styles, while the more classic interpretations of this variety come in the flinty, herb-scented wines from Sancerre and Pouilly-Fumé.

Pinot Grigio is a white variety currently in vogue for its easy-drinking, understated qualities. The most rewarding versions, however, tend to be richer in style and grown in Alsace, New Zealand or Italy’s Alto Adige, where it is more commonly known as Pinot Gris.

Riesling is, by contrast, one of the least understood white varieties, often overlooked because of its (unfair) association with poor quality German wine. In fact, Riesling can make some of the most rewarding and complex white wines in the world, and in a range of styles from the delicate, off-dry German whites (great with spicy Asian food) to the steely, racy wines of Australia.

Two red varieties that deserve a final mention are Syrah and Pinot Noir. Syrah, also known as Shiraz, can make wines in a range of styles according to where it’s grown. Warmer areas tend to make for big, hearty reds (think Australia’s Barossa Valley), while cooler areas (the northern Rhône, Chile’s San Antonio) give wines with a more restrained, pepper-and-meat character.

Pinot Noir, meanwhile, is celebrated as the wine lover’s red variety. Difficult to grow and make well, it needs a specific balance of conditions – not too warm, not too cold – to make the kind of expressive, subtle and delicate reds that so endear it to wine aficionados. Perhaps its finest expression can be found in Burgundy, though the cooler areas of California, Chile, Australia and New Zealand are also starting to produce excellent Pinot.