People drink beer with their eyes, and in the last couple of hundred years ultra-clear beers, which had been filtered removing yeast and small proteins, were the most popular due to appearance and familiarity.

Unfiltered beer is quite simply beer that has not been filtered, nothing has been removed, allowing for a more complex flavour and aroma. Flavour molecules attach themselves to proteins during fermentation, so leaving them in produces a greater roundness and mouthfeel, whilst still retaining a crisp, refreshing taste.