An article from Colour Lovers about hair color

I found this article that might interest you. It is not a hair based website, but a site for designers about all types of colors. There is some very good information here about the history of haircolor as well as a little bit of chemistry and might make conversations with your haircolorist more clear. I do have a few things that I want to clarify, however:

Permanent Color
The longest-lasting of hair dyes, permanent color cannot be washed out. It contains both ammonia and peroxide, which raise the cuticle of the hair in order to allow the tint to penetrate to the cortex and lighten the hair by breaking up the melanin that gives hair its natural color, fundamentally changing the shade of the hair. Since the color is (true to its name) permanent, bringing hair back to its original color requires a new dye job.*