These products can be divided into three categories according to their colour-fastness:
The first 2 categories are non-oxidative (non-permanent) hair dyes and are used for temporary colour changes.
The group of permanent hair dyes comprises oxidative hair dyes and represents 70–80% of the colouring products market in Europe. The colouring is resistant to shampooing and grows out over time. The colours are produced directly on and in the hair from colourless precursors (developer and coupler) through a chemical reaction in the presence of hydrogen peroxide as an oxidising agent. This results in the hair being coloured right through and the colour being resistant to shampooing.