Well, to me, the real point of drinking wine is to get the most pleasure out of every glass. And, as with many things in life, the most pleasure comes to us once we really understand the subject. With wine, the best way to gain this kind of fruitful understanding is to use your senses as you drink. Sensing what a wine looks like, smells like, feels like, as well as tastes like reveals the truest character of the wine and brings the truest pleasure to the drinker. Looking at a wine gives you hints about its maturity, the grape variety, and sometimes even how the wine was made.
Color is a clue to a wine's age.
White wines darken as they get older, but red wines do the opposite, losing color and turning lighter with time. Color also tells you about grape variety. Because color pigments in grape skins differ from varietal to varietal, so do the ultimate colors of the wines. Pinot Noir grapes make wine that's light vermilion. Nebbiolo almost black.