Bitters are a key cog in the cocktail world and these little drops of wet-stuff can pack a mighty flavour. Bitters are made with various bitter herbs, barks and other flavours, with a base of alcohol. Bitters are more bitter than your work colleague Brenda when you are off for two weeks on your holibobs and she’s just got back from a rainy week Skegness. So we wouldn’t recommend drinking a bitter neat. These bring a great complexity and depth to your favourite Old-Fashioned, though.