The three things that shape wine
Almost everything about a wine's character is determined by three factors: the grape variety (or varieties) it is made from, the climate and soil where the grapes were grown, and the winemaker's choices during production. The same grape variety grown in a cool climate produces a different wine from one grown in a hot climate.
Old World versus New World
Old World wines (France, Italy, Spain, Germany, Portugal) tend to be more restrained in fruit expression, higher in acidity and lower in alcohol — characteristics of cooler climates and centuries of tradition. New World wines (California, Australia, Chile, South Africa, New Zealand) tend to be more fruit-forward, fuller-bodied and higher in alcohol — characteristics of warmer climates and a less tradition-bound approach.
The grape varieties to know
For white wines: Chardonnay (versatile, from lean and acidic in Chablis to rich and oaky in California), Sauvignon Blanc (grassy, citrus, high acid), Riesling (aromatic, high acid, ranges from bone dry to very sweet). For reds: Cabernet Sauvignon (full-bodied, tannic, blackcurrant), Pinot Noir (lighter, cherry, earthy), Malbec (plummy, soft tannins), Merlot (medium body, plum, softer than Cab Sav).
How to taste
Hold the glass by the stem (to avoid warming the wine with your hand). Observe colour. Swirl (to release aromatics). Smell (identifies primary fruit aromas, secondary fermentation aromas, and tertiary aged notes). Taste: note sweetness, acidity (how the wine makes your mouth water), tannin (the drying sensation in reds), alcohol (heat at the back of the throat), and finish (how long the flavour persists after swallowing).