Mathematicians have worked to find a formula for beauty, but the best they have done is make a scatterplot that looks like Snow White. Be the fairest one of all with this Groupon.

Choose from Three Options

• $19 for a Moroccanoil deep-conditioning treatment, blowout, and style (a $45 value)
• $29 for a Moroccanoil deep-conditioning treatment, haircut, and style (a $75 value)
• $49 for a Moroccanoil deep-conditioning treatment, haircut, style, and all-over color (a $140 value)

Everyone knows shampoo cleans hair, but how conditioner works is mostly still a tangle. Read Groupon’s study of the process to understand this essential styling step.

Hair Conditioner: Ticket to a Molecular Makeover

Though human hair may look smooth, each strand’s outer layer—the cuticle—is actually quite rough. Under dry conditions, the tiny scales that cover its surface can often become raised and brittle, causing hairs to tangle more easily and lose their shine. Conditioners aim to correct this problem by bonding a particular class of molecules, called cationic surfactants, to the cuticle. This is possible because keratin, the protein that composes most of the hair shaft, bristles with negative ions, which attract the positively charged surfactants, coating each thread in a thin film that weighs it down and reduces frizz. (The negative charge of keratin is also what causes static whenever positive ions are stripped from the hair—the static that makes it possible to stick a balloon to the wall, say, or to power a miner’s headlamp.)

The other ingredients in conditioner don’t always need ions to do their jobs well. Humectants suck in water from the surrounding air, moisturizing the hair, and oils simply penetrate the cuticle. Glossers coat the hair with light-reflecting polymers, increasing shine, whereas other ingredients raise the acidity level of the conditioner, which helps protect the hair’s protein structure.