The character of most wines is defined largely by the grape variety, and it is a source of innocent pleasure to be able to identify which variety it is without peeking at the label. Here are some of the characteristics to look for in wines from the most widely planted varieties.
White
Chardonnay: Colour from pale to straw gold. Aroma can evoke peach, pineapple, sweet apple. Flavours of sweet apple, with creaminess or toffee from oak contact.
Fiano: Italian variety said to have been cultivated from ancient Roman times in the Campania region of southern Italy. Now widely planted on the mainland and in Sicily, it makes dry but soft wines of colours ranging from pale to pure gold with aromas of honey, orchard fruit, almonds and candied apricot. Well-made examples have beautifully balanced nutty-fresh flavours. Fiano is becoming fashionable.
Pinot Grigio: In its home territory of northeast Italy, it makes wines of pale colour, and pale flavour too. What makes the wine so popular might well be its natural low acidity. Better wines are more aromatic, even smoky, and pleasingly weighty in the manner of the Pinot Gris made in Alsace -; now being convincingly imitated in both Argentina and New Zealand.
Riesling: In German wines, pale colour, sharp-apple aroma, racy fruit whether dry or sweet. Faint spritz common in young wines. Petrolly hint in older wines. Australian and New Zealand Rieslings have more colour and weight, and often a minerally, limey twang.
Sauvignon Blanc: In the dry wines, pale colour with suggestions of green. Aromas of asparagus, gooseberries, nettles, seagrass. Green, grassy fruit.
Semillon: Colour can be rich yellow. Aromas of tropical fruit including pineapple and banana. Even in dry wines, hints of honey amid fresh, fruit-salad flavours.
Viognier: Intense pale-gold colour. Aroma evokes apricots, blanched almonds and fruit blossom. Flavours include candied fruits. Finish often low in acidity.
Red
Cabernet Sauvignon: Dense colour, purple in youth. Strong aroma of blackcurrants and cedar wood ('cigar box'). Flavour concentrated, often edged with tannin so it grips the mouth.
Grenache: Best known in the Côtes du Rhône, it tends to make red wines pale in colour but forceful in flavour with a wild, hedgerow-fruit style and hints of pepper.
Merlot: Dark, rich colour. Aroma of sweet black cherry. Plummy, rich, mellow fruit can be akin to Cabernet but with less tannin. May be hints of bitter chocolate.
Pinot Noir: Colour distinctly pale, browning with age. Aromas of strawberry and raspberry. Light-bodied wine with soft-fruit flavours but dry, clean finish.
Sangiovese: The grape of Chianti and now of several other Italian regions, too. Colour is fine ruby, and may be relatively light; a plummy or even pruny smell is typical, and flavours can evoke blackcurrant, raspberry and nectarine. Tannin lingers, so the wine will have a dry, nutskin-like finish.
Shiraz or Syrah: Intense, near-black colour. Aroma of ripe fruit, sometimes spicy. Robust, rich flavours, commonly with high alcohol, but with soft tannins. The Shiraz of Australia is typically much more substantial than the Syrah of the south of France.
Tempranillo: Colour can be pale, as in Rioja. Blackcurrant aroma, often accompanied by vanilla from oak ageing. Tobacco, even leather, evoked in flavours.
There is more about all these varieties, and many others, in the chapter 'What Wine Words Mean'.