context: It can be long and wavy, short and straight, frizzy and unmanageable, or smooth and shiny. Hair comes in many different lengths, styles, colors, and textures. Yet just about everyone -- no matter what kind of hair they have -- falls prey to at least one hair problem at some point in life. This article covers some of the most common hair dilemmas, from hair loss to greasy hair. Some people consider gray hair as something that makes them look distinguished; for others, it's a reminder that they're getting older. How ever you feel about it, gray or white hair is pretty much inevitable with age (if you're fortunate enough to still have hair in your later years). Scientists have put a lot of effort into investigating the cause of gray hair, and they believe they've gotten to the root of the problem. Hair gets its color from a pigment called melanin, which is produced by melanocyte cells in the hair follicles. Researchers have discovered that melanocytes endure cumulative damage over the years, which eventually leaves them unable to produce melanin. Studies have cited DNA damage and a buildup of hydrogen peroxide in the follicles as possible causes of this disruption in melanin production. Without melanin, the new hair that grows in has no pigment, which makes it appear gray, white, or silver. Some people start to go gray young -- as early as their teens. When graying begins usually is determined by genes, so if your mother or father became gray early, you may, too. If you are one of those people who don't find gray hair distinguished, you can easily cover your gray with one of the many different hair dyes available. Normally, hair goes through a regular growth cycle. During the anagen phase, which lasts two to six years or longer, the hair grows. During the telogen phase, which lasts about three months, the hair rests. At the end of the telogen phase, the hair falls out and is replaced by new hair. The average person loses about 100 hairs each day. Hair loss also can have other causes, including drugs or disease. As they age, men tend to lose the hair on top of their head, which eventually leaves a horseshoe-shaped ring of hair around the sides. This type of hair loss is called male-pattern baldness. It's caused by genes (from both parents -- the idea that men take after their mother's father is a myth) and it's fueled by the male hormone, testosterone. In female-pattern baldness, the hair loss is different -- it thins throughout the top of the scalp, leaving the hair in front intact. A number of disorders can cause the hair to fall out. People who have an autoimmune condition called alopecia areata lose hair on their scalp, as well as on other parts of their body. Other health conditions that can cause excess hair loss include: Medications such as antidepressants, retinoids, NSAIDs, blood thinners, birth control pills and other hormonal treatments, high blood pressure medications, chemotherapy, and radiation Severe infections Major surgery Overactive or underactive thyroid Other hormonal problems Severe stress Autoimmune diseases, such as lupus Fungal infections of the scalp Pregnancy and childbirth Exposure to chemicals such as thallium, boron and arsenic Iron-deficiency anemia Certain hair care practices, such as wearing tight ponytails or weaves, or regularly bleaching or perming the hair, can also lead to hair loss. Some people compulsively pull out their hair. This psychological disorder is called trichotillomania. When hair loss is related to a medication, stopping the drug usually prevents further hair loss, and the hair will eventually grow back. Hair also tends to grow back after most illnesses, radiation therapy, or chemotherapy. Wearing a wig or hat can hide the hair loss until the hair returns. Hair transplants are a more permanent hair-replacement solution. Hair lost to male-pattern and female-pattern baldness won't grow back on its own, but there are medications that can help slow hair loss and even regrow hair. Minoxidil ( Rogaine) is a topical medicine that is available over the counter to treat men and women. Finasteride ( Propecia) is a pill that is available to men only by prescription. Injectable cortisone may also help regrow hair lost to certain conditions. Other hair-loss treatments include injections with platelet-rich plasma, low-level light devices (for home use), hormonal replacement therapy (for perimenopausal patients), and neutraceuticals (pills or liquids taken by mouth such as prenatal vitamins). Blow-drying, straightening, highlighting, and perming regularly can wreak havoc on hair, leaving it brittle, broken, and unmanageable. Split ends and dry hair are just two casualties of overstyling. Excessive styling and heat can cause split ends, which occur when the protective outermost layer of hair (the cuticle) is damaged and peels back. Some treatments for split ends include: Brush gently with a soft, flexible hairbrush; don't overbrush. Avoid towel-drying. If you do dry your hair with a towel, rub it gently. Use a conditioner, and leave on a deep conditioner about once a week. Hair needs moisture and a certain amount of oil to keep it looking healthy. A number of things can dry out hair, including: Washing it too often Using a harsh shampoo Excessive blow-drying or use of a curling iron or straightening iron Exposure to sun, wind, and dry air Perms and dyes Poor nutrition Certain medications To keep the moisture in your hair, try these tips: Don't wash your hair every day unless you have a scalp condition such as dandruff which needs daily shampooing for control. When you do wash your hair, use a gentle shampoo that's designed to infuse moisture into dry hair. Also, use a conditioner daily. Limit blow-drying and use of hot irons, hot rollers, or curling irons. Increase the time between hair treatments, such as dyes and perms. Wear a hat on cold, windy days and put on a bathing cap when swimming. The scalp contains a natural oil called sebum, which helps keep the skin lubricated. Sebum is produced by the sebaceous glands. Sometimes these glands work overtime and produce too much oil, leading to a greasy scalp. Greasy hair can look dull, limp, and lifeless, and it may be more difficult to manage. To treat greasy hair, try washing with a gentle shampoo that is specially formulated to control sebum.