What distinguishes black tea from other types of tea is that it is 100% oxidized. This results in a dark brown leaf and gives the liquor a dark amber colour. This kind of tea releases the most amount of tannin and can be drunk with or without milk. It is also the tea that deteriorates the slowest and therefore can stay fresh for up to two years if kept in an airtight container. It is the most consumed tea variety in the west especially by the Irish who at the moment consume the most tea per person in the world.