response: Some of the main reasons for it would be covering gray or white hair, be fashionable or even to restore hair due to hairdressing discoloring or sun bleaching.
original_response: Most people dye their hair to hide gray. I did it to hide my blonde hair.
history: My younger daughter hair once had blue hair! She loved it! Sounds interesting, does she partake a lot in hair coloring or the practice of changing her hair color? No, it costs a lot and she's always changing her mind you know. I don't really get the purpose for it either.
knowledge: The main reasons for this are cosmetic: to cover gray or white hair, to change to a color regarded as more fashionable or desirable, to restore the original hair color after it has been discolored by hairdressing processes or sun bleaching.