The Stem - Allows you to hold your wine glass without the heat from your hands warming your wine, and without creating smudges on the bowl which will distract from the visual enjoyment of your wine
The Bowl – Serves a myriad of purposes; here you'll find the most variation between glasses. The bowls of all wine glasses will be tapered upward with a slightly narrower opening at the top than at the bottom. This shape helps to capture and distribute the wine's aroma toward your mouth and nose.
The bowls of wine glasses are also designed to allow an amount of surface area appropriate to the wine - red wine glasses will have a larger amount of surface area for the wine to allow it to breathe, while white wine glasses will have a smaller amount of surface area. Champagne glasses will have a very small amount of surface area for the wine so that it retains its carbonation
The Rim – Imperative to achieving the full experience from your wines. The thinner the rim, the less the glass distracts from the wine as you sip; a good wine glass will have a "cut" rim that is smooth to the touch and does not inhibit the wine as it flows out of the glass. Less expensive glassware may have rims that are rolled or bumpy – while still functional, and very much practical for everyday use, these wine glasses may distract from the wine itself
The Color – The best wine glasses are crystal clear to allow the beauty and subtleties of the wine to show through. Colored glasses and those with decorative accents may offer a beautiful appearance, however, if showing off your wines, clear glasses are the way to go.
Red wines are best served in large wine glasses, like these red wine glasses. The bowls of these glasses will be fuller and rounder with a larger opening than other wine glasses of similar capacities in order to allow you to dip your nose into the glass to detect aroma. This bowl style is also imperative because the complex aromas and flavors of red wine demand a glass with a larger surface area to ensure that the wine comes in contact with more air.
A specific type of red wine glass, the bordeaux glass, is taller than traditional red wine glasses, yet the bowl is not quite as large. It is designed for full bodied, heavier red wines such as Cabernets and Malbecs. The tallness of the glass allows the wine to proceed directly to the back of the mouth to maximize its flavor.
Another style of red wine glass, the burgundy glass, is designed for lighter, full-bodied wines such as Pinot Noir. It is not as tall as the Bordeaux glass, but the bowl is larger than the Bordeaux glass, directing the wine to the tip of the tongue to taste its more delicate flavors.