Short definition
Wine glasses with stems that keep your hand away from the bowl, preventing body heat from warming the wine.
The stem exists so you hold the glass without warming the wine. The bowl shape matters more than most people think — a wide bowl funnels aromas toward your nose, while a narrow flute preserves bubbles in sparkling wine. You do not need twenty different glass shapes. One good all-purpose wine glass with a tulip-shaped bowl handles 90% of wines. Just avoid thick-rimmed tumblers that muffle everything.