Purple shampoo has pretty much become a staple for blondes who invest in cool-toned hues. Here, one stylist shares how toning shampoos can be helpful for all hair colors looking to counterbalance ...

Ammonia-oxidizing bacteria are the “nitrofiers” in the bottom right of this diagram on Earth’s nitrogen cycle. Image Credit: Eme Chicano via Wikimedia Commons // CC0 1.0. In order to really ...