I can't say for the world but it is popular at least in Copenhagen. 18% of the men and 75% of the women have used hair dyes according to an University of Copenhagen study!
Just be careful, if you spill it, it makes a big mess!  And I never realized until recently that 75% of women in Copenhagen have used hair dye!
I like to color my hair to cover gray, do you color your hair? No hair to color actually. Do you get yours done? If so, is it done at home or do you go get it done professionally by a hairdresser? I'm leaning towards going to a hairdresser, I've made quite a few mistakes doing it on my own. But I've seen so many people buy products, it must be a big business right? I can't say if it's a big business but in 2011 home coloring in the US hit $1.9 billion! I think one reason that it hit such a number is some of the products are really expensive. Brands probably charge 3x the cost to make such things! I had a friend restore their hair color too, can you tell me about that? Sure, if they tried to restore to their original hair color it may have been because their hair was discolored through a hairdressing process or perhaps it was due to sun bleaching. I see, that's really helpful to know and I'll definitely keep that in mind when I'm doing it. Is hair coloring super popular?
Today, hair coloring is very popular, with 75% of women and 18% of men living in Copenhagen having reported using hair dye according to a study by the University of Copenhagen.