What is the purpose of the outward taper in a beer glass?

The outward taper in a beer glass primarily supports head retention. This design feature creates a wider mouth at the top of the glass, which encourages the formation and maintenance of foam when beer is poured into it. The head, or foam, is crucial for aroma and flavor release, which enhances the overall drinking experience. The shape of the glass helps trap the volatiles, allowing the drinker to enjoy the full bouquet of aromas present in the beer.

While other shapes and designs in glassware may serve different functional purposes, the specific role of the outward taper is to optimize the structural characteristics necessary for retaining a beer's head. The head not only contributes to the aesthetics of the serving but also helps to balance the flavors and contributes to the texture of the beer as it is consumed.