Hair is every person's crowning glory, and this is why beauty companies earn millions selling everything from shampoo to spa treatments to achieve those silky tresses. However, there are some beliefs about hair care that just aren't true.

One of these, according to the Huffington Post, is that blowdrying hair on a daily basis is wrong. While blowdrying hair will cause damage to the hair's surface, allowing it to dry naturally can actually damage the inside of the hair.

Whenever hair is exposed to water for extended periods of time, it actually swells up and puts pressure on the proteins that keep hair intact.  So in order to protect the hair, the best bet is to actually allow the hair to dry naturally until the hair is 75 percent dry, then put the blowdryer to a low heat setting to finish it off.

Another myth is that dandruff is caused by a dry scalp. However, the truth is that dandruff is caused by a type of yeast that thrives in an oily environment, the Huffington Post reports. So for those suffering from a flaky scalp, the best solution is to wash their hair every day with a medicated shampoo.

The third myth is that stress causes grey hair, but the real culprit is apparently genetics and aging. As for the myth that brushing hair daily makes it more healthy, people should proceed with some caution. Brushing causes the distribution of natural oils, which is good, but too much brushing can create friction and cause frizz and thus actually break the hair.

Another common myth is that frequent cuts can make your hair grow longer faster. But Joshua Zeichner, MD, director of cosmetic and clinical research in dermatology at Mount Sinai Hospital in New York City, told Health there's no basis to that myth.

"Trimming your hair doesn't affect growth," he said. "That happens at the scalp." Melissa Piliang, MD, a dermatologist and hair specialist at the Cleveland Clinic, said the only upside of frequent cuts is that "frayed ends make hair look thinner and cause breakage, so when you cut them off, your hair appears fuller."