What does the “legs” of a wine indicate?

The concept of "legs" in wine refers to the droplets that form and slide down the inside of a wine glass after swirling. These droplets are a visual clue regarding the wine's viscosity and alcohol content. When a wine has a higher alcohol level or greater viscosity, it tends to display more pronounced legs. This phenomenon occurs because higher alcohol content can create a thicker texture, which allows the droplets to form and cling to the glass longer before falling back. Thus, observing the legs can provide a sommelier with insights about the wine’s physical properties, specifically relating to its body and alcohol level.

The other options do not accurately reflect what the legs represent. Sweetness level is typically assessed through taste rather than visual observation, and the age of a wine is influenced by various factors that can't be solely determined by the appearance of legs. Legibility of the label pertains to the packaging and presentation of the wine, which is unrelated to the sensory analysis of the wine itself.