The term FROTH ON BEER is a four-letter word, HEAD. This term is used to describe the foam that forms on top of beer when it is poured into a glass. The foam is created by the carbon dioxide in the beer and is often referred to as 'HEAD' or 'FROTH'. The HEAD of a beer can range from a thin layer to a thick layer, depending on the type of beer and how it is poured. The HEAD of a beer can also affect the taste of the beer, as it can add bitterness or sweetness.