"Split ends are damage done to your cuticle," says hairstylist Levi Monarch. "Once it gets so damaged to the point it starts to split, the only way to fix it is by cutting it off."

So how does this happen? The same way you get damage elsewhere on your hair: Heat, chemical treatments, physical wear and tear, and environmental aggressors like the sun. The worst culprit, however, is heat. "And one thing that causes a lot of damage is actually metal brushes, especially when used with heat from blow-dryers," says Monarch. "The metal bristles retain heat from your hot tools, which ends up increasing the damage done to the hair." (He recommends switching to a boar bristle brush, which is softer on your hair.)

So at this point, you're likely wondering why I'm suggesting split-end products at all. And to that I say, Valid point! It's disingenuous to claim that this product category is somehow ridding your hair of frayed, damaged ends, as what you're seeing is really just superficial care. But once you get over the mental hump that these aren't going to save your hair from all damage forever, you can start to see them for what they are: a styling tool and, more importantly, preventive care.

"What split-end menders do is fill out your cuticle and act like a temporary glue to bond the tips together; in some cases they increase shine so you can apply it after you've done your hair to make the ends look more put-together," says Monarch. "But what you really need to pay attention to is the protective layer, like a thermal or UV shield. This way, you can put it on the ends before styling to keep your hair from getting them in the first place."