Black tea is the most oxidized (fermented) type of tea. It has a darker liquor and generally a stronger flavour compared to less oxidized teas. Hong Cha is one of the more commonly produced type of teas as it is one of the most commonly known.
In Europe and America Red tea is usually called Black, this is because in there areas the name of the tea was based on the colour of the leaf rather than the colour of the liquor.