What should you always do to a glass before serving beer?

Rinsing the glass in cold water before serving beer is essential because it helps to remove any dust or contaminants that could affect the flavor and aroma of the beer. This practice also chills the glass slightly, which can enhance the drinking experience, especially for certain styles of beer. A cold glass can prevent foam from dissipating too quickly and helps maintain the beer's ideal serving temperature. Furthermore, rinsing can create a better head retention by conditioning the inside of the glass, allowing for a more enjoyable presentation and taste.

While drying, chilling, or leaving the glass uncleaned might seem like viable options, they do not effectively prepare the glass for serving beer. Simply drying can miss removing residues, chilling alone doesn’t necessarily eliminate contaminants, and having a dirty glass can spoil the entire experience. Thus, rinsing the glass stands out as the most beneficial step in serving beer properly.