Drinking wine is not the same as tasting wine. Drinking is usually in social settings such as a party or at a restaurant.  Tasting is done when your goal is to learn about wines. Drinking wine won’t involve any more of a thought process than either you like it or you don’t.

Why taste?

Varieties of wine
There are so many wines available there is no way you can know each wine. What you can do is find a few trusted wines you can go to. Also, you can begin to generalize about styles. Such as, you can decide that you don’t like cheap Chardonnays, but cheap Merlots are fine. You might decide you love Zinfandel or Cabernet.
Price segments
Obviously, you want to learn about varietals and decide if you prefer Pinot Gris or Sauvignon Blanc. But it goes deeper than that. You’ll want to segment by prices. Things like how inexpensive can you go with a Sauv Blanc before you don’t like them. Or can you really tell much of a difference between a $30 Cabernet and a $60 one?
What is the setting?
Something else to consider is if you’ll be drinking the wine with a meal or on its own. For instance, a Sauvignon Blanc may be better with food than Chardonnay. Also, a fruit-forward, high alcohol Zinfandel is probably not as good of a pasta wine as would be an Italian Barbera.
And some wines seem better in hot weather vs. cooler. Things like Sauvignon Blanc seem to taste better in hotter weather than a heavy Cabernet.

Getting ready to taste

Temperature
The wine has to be at the proper temperature. Too cold and you get very little flavors or smells from the wine. Too warm and it may be astringent and unpleasant. Usually, a cool cellar temperature (about 50 degrees) is best for whites and a cool room temp (low 60s) for reds.   A white wine straight out of the refrigerator or a red straight out of a cool cellar is too cold because you won’t get many flavors from the wine.  So give the wine some time to warm a bit if necessary.
Glassware
Wine glasses with a stem are what you want for tasting so you can hold the glass by the stem and not transmit any warmth from your hand to the wine. I suppose that’s why beer mugs got popular.

How to taste

Wine tasting comes down to sight, smell, taste, and aftertaste.
Sight
Sight is, well, white or pink or red. What you see doesn’t tell you much and isn’t that important. The only thing you may notice is some brown color right at the edge where the wine meets the glass. That could mean the wine is pretty old or maybe oxidized, but that still doesn’t matter as it’s your taste and smell that are important.
Nose
Smelling, or the nose of a wine, is actually the key to it all. Most of what you get from a wine is actually via your smell plus your sense of smell is much more sophisticated than your taste buds. You may smell things that remind you of different fruits, herbs and spices, or other things. Sometimes you smell something unpleasant which tells you this wine isn’t for you. People’s memories of odors are better than any other sense memory.  What you pick out in the wine will be different from what others do.
How you smell the wine is important. To get the most you have to get a bit of oxygen in there. One way is swirling the wine in your glass so you’ll want a glass of wine that’s less than half full. The best way to see how this works is pour a wine and stick you nose as far into the glass as you can get it and inhale strong and deep. Next swirl the wine around for about 15 seconds and do it again. You’ll notice a whole lot of things going on the second time that you didn’t pick up before you swirled.
Taste
To taste you can add oxygen to the wine once it’s in your mouth to help bring out flavors. There are a couple ways to do this. The least messy is just to slosh it around in your mouth as you would mouthwash before swallowing the wine. The other is a bit hard to explain without a visual demonstration but it involves sucking air in between the teeth while the wine is in your mouth.
From tasting you may pick up things like acidity, sweetness, tannins, and alcohol.
Acidity can be picked up as bright, sour, or mouth-watering–it’s different for different wines and different people. Low acid wines can be called soft or flat. Higher acid is generally best with food; lower acid wines are easier to sip on.
Sugar is sometimes confused with fruitiness, oak, or alcohol as all can be perceived as sweet.
Tannins are mouth-drying like black tea. High tannin wines are usually call dry, but also a wine with no sweetness at all is dry. This is where you want the acids, tannins, and sugar all in balance so no one of them overwhelms the others.
Alcohol is something you can pick up as sweet or it can come across as heat. Many New World style wines (those not from Europe) can show heat from too much alcohol.
Finish
As with the sight, the aftertaste, or finish, of a wine doesn’t mean too much either. Sometimes people say it’s a long or short finish and the experts have decided long is better. Sometimes you may pick up something unpleasant in the aftertaste and this is what really matters to you.

Now what?

Well, it comes down to whether you like it or not, but also why.   What do you like or not like and file this away in your head or on paper so you’ll know more next time.  The first objective is to discover wines you enjoy with the ultimate goal being to find the perfect wine for whatever the occasion.
Once you find a wine that you like, start building your wine stock at home. You will want to have plenty on hand to enjoy with visiting friends our by yourself.