What is "flat"?

Flat is a term used to describe a type of drink that has lost its effervescence or carbonation. This can occur over time as a result of exposure to air, or as a result of being shaken or stirred, causing the carbon dioxide to escape from the liquid. Flat drinks can include sodas, sparkling water, and certain types of beer, and are often less enjoyable than their fizzy counterparts due to their lack of bubbles and fizziness. Flat drinks can also have a less appealing taste and mouthfeel, as the carbonation can play a role in enhancing the flavor and texture of the drink. While flat drinks can still be consumed, they may be less satisfying and enjoyable than their carbonated counterparts. To prevent drinks from going flat, they should be stored in airtight containers and consumed promptly after opening.