Let’s start with acid:
Of course, acid has a tart flavor. Incidentally, if you refer to high-acid wine as sour you’re going to get a very sour look from the winemaker. In wine parlance, sour means spoiled, as in gone to vinegar!

If you want to become acquainted with the tart flavor of relatively high-acid wine, some common white examples are sparkling wine, Sauvignon Blanc and Riesling. Northern Italy turns out a lot of lean, zippy reds.

Some wines, especially reds, are so flavorful that it’s difficult to taste the acid. Usually, you can still gauge it. As you taste the wine, notice the way your mouth begins to water, especially along the sides of your tongue and under it. Thus, the birth of the phrase “mouth-watering acidity.” Now that you’ve noticed it, you’ll begin to differentiate the levels as you taste different styles of wine. Generally, white wines are higher in acid than reds. Well-made dessert wines can really turn on the water works in your mouth because the sweetness needs to be balanced by a high level of acidity.

Why do you care? Acid is important because it keeps the wine fresh and lively on the palate. It has a cleansing effect and makes the wine easy to pair with food. Acid is a great, natural preservative! Wines that are high in acid (but balanced) will have fairly long lives and a better chance of retaining their fruitiness and freshness as time goes by.

The source: The grapes, although acid additions are permitted in many wine regions. As the grapes ripen, the sugar increases and the acid decreases. At harvest time, timing is everything!

Descriptions: Crisp, lively, bright, racy, nervy, vitality
Antonyms: Flat, flabby, soft, dull, insipid

Tannin
Do you have a sudden urge to brush your teeth after tasting red wine? Then you recognize tannin – it’s that simple. It runs around your mouth seeking out protein and then clings to it, which explains the drying sense of grip on your gums – all over your mouth, really – and the furry teeth. The flavor of tannin is extremely bitter, so winemakers try to craft the wine in such a way that you feel it, rather than taste it. As you taste your wine now, you will probably remember other wines you’ve tasted that were more tannic or less tannic, so you'll begin to recognize relative levels.

Acid accentuates the hardness of tannin, so high-acid wine that’s also tannic can be hard to enjoy when it’s young. As the wine ages, the tannin enlarges with oxidation and gradually falls out of the wine as part of the sediment. So, the wine gradually softens and the texture becomes more velvety over time.

Why do you care? Tannin is an important part of the texture of red wine – when managed properly it gives it a nice chewiness. Like acid, tannin is a natural preservative. It's part of a group called polyphenols, which are anti-oxidants that prolong the wine's life. The more tannic the wine, provided it's well made and well-balanced, the longer its life in the bottle when stored properly.

The source: The biggest source of tannin in wine is the grape skins. Other sources are the seeds, stems and oak (wine barrels contribute wood tannin if they're relatively new). Red wines are almost always higher in tannin than white because the winemaker must ferment the juice and skins together to get the purple color. Whites receive little or no juice to skin contact.

Descriptions: Astringent, drying, grippy, chalky, chewy, hard, coarse
Antonyms: Soft, smooth, silky, round, velvety, mellow