Age spots, also known as "liver spots" or lentigines (lehn-TIHJ-ih-neez), are flat, irregular spots of brown pigment, as opposed to moles, which tend to be raised and round.

After contact with certain substances, some individuals may experience an allergic reaction known as contact dermatitis (der-muh-TIGH-tihs). This usually produces a red or swollen, irritated rash on the skin, though it may cause small, itchy bumps called hives.

Everyone loses hair as a natural part of the growth cycle, shedding from 50 to 150 hairs on an average day. In some individuals, however, hair is lost very rapidly, the growth of replacement hairs is extremely slow, or regular hairs are replaced by shorter, thinner ones.

Birthmarks are usually divided into two categories: vascular and pigmented. Vascular birthmarks include deep red marks such as port wine stains, which are caused by blood vessels.

Contrary to what some people believe, the tiny, dark spots known as blackheads aren't caused by surface dirt. Blackheads are simply pores which have become clogged by a plug of oil and dead skin cells.

The lines that run from the bottom of the nose to the corners of the mouth are known as the nasolabial (nay-zoh-LAY-bee-uhl) folds, or cheek folds. Nasolabial folds are present in everyone, but tend to become exaggerated as you age due to gravity, repetitive facial expressions, and loss of skin elasticity.

Most cases of thinning hair are an inherited problem due to the male hormone androgen (AN-droh-jin). This common form of hair loss is called pattern baldness, or androgenetic alopecia (al-oh-PEE-shuh).

Hemangiomas (hee-man-jee-OH-muhz) are a type of benign tumor made up of masses of blood vessels. These vascular birthmarks have a red, bumpy appearance, also giving them the name "strawberry marks.

Hives, known medically as urticaria (ur-tih-CAIR-ee-uh) are red, itchy, swollen spots that can occur as an allergic reaction to many possible triggers.

The laser is a device that converts electrical energy into an intense beam of light which can then selectively cut or vaporize tissue and blood vessels.

So-called "liver" or "age" spots are typically flat, brown marks up to an inch in diameter. They're the result of concentrated amounts of the skin pigment melanin (MEHL-uh-nihn).

As you age, your skin undergoes a number of changes and also begins to reflect earlier damage from the sun in the form of wrinkles and/or age spots. The oil glands produce less sebum (SEE- buhm), often causing dryness or itching.

Moles are flat or raised spots on the skin caused when pigment cells called melanocytes (mehl-AN-oh-sytes) grow in a concentrated clump. These spots may be pink, brown, black, yellowish, or bluish and may occur anywhere on the skin.

Poison ivy, sumac (SOO-mack), and oak are plants whose sap causes an allergic reaction in most people who contact it. Within 12 to 48 hours, sensitive individuals develop a red rash which begins to itch and swell.

Port wine stains are vascular malformations that usually affect the face or neck, though they may appear in other areas. Present at birth, they typically begin as flat, irregular, pinkish stains, but may darken to red or purple later in life.

As a result of their compromised immune systems, patients with HIV (H-I-V) or AIDS (aids) are vulnerable to a number of skin diseases. Many of these are common skin disorders, but in HIV or AIDS patients, the symptoms tend to be much more severe.

Most traces of a tattoo can be removed with a number of techniques, though some degree of scarring is likely to result. The suggested method usually depends on factors like the tattoo's size and location, what dyes were used, and how they were introduced into the skin.

Vascular birthmarks are those which derive their color from blood vessels, as opposed to skin pigment. For this reason, vascular marks tend to be red, bluish, or purplish in color.

While birthmarks like hemangiomas (heh-Man-jee-OH-muhz) will eventually go away, parents may choose to treat them so a child can avoid the teasing or emotional trauma that may accompany such marks.

Wrinkles are caused by damage from UV (U-V) radiation and a variety of changes in your skin that occur with age. Lines also tend to develop in areas where you have repeated expressions.