Alopecia (al-oh-PEE-shuh) is the medical term for baldness. Most baldness affects the scalp, and in men, sometimes the beard. The hair loss may occur in certain regions, in isolated patches, or as an overall thinning.

Athlete's foot, known medically as tinea pedis (TIHN-ee-uh PEHD-ihs), is a fungal infection of the feet. Common symptoms include peeling, cracking, or scaling skin between the toes, especially the fourth and fifth toes.

Eczema (EHK-zih-muh) is a general term for several types of skin inflammations. The most severe form of eczema is called atopic dermatitis (ay-TAWP-ihk dehr-muh-TYE-tihs), or AD (A-D).

Fungi (FUHN-gye) are a group of plantlike organisms that includes mushrooms, mold, and yeast. But unlike plants, fungi can't produce their own food and so must grow on a host.

Pityriasis rosea (Piht-ih-RYE-ah-sihs Ro-ZEE-uh) is a harmless rash of unknown origin that typically affects those between age 10 and 35, though it may occur at any age.

Seborrheic dermatitis (sehb-oh-REE-ihk der-muh-TIGH-tihs) is a skin inflammation marked by red, oily, flaking skin, especially on the scalp. Other areas commonly affected are the eyebrows, eyelids, sides of the nose, the mid-chest, and the skin behind the ears.

A seborrheic keratosis (sehb-oh-REE-ihk kehr-uh-TOH-sihs) is a non-cancerous growth in the outer skin layers that may resemble a waxy wart. They usually appear above the waist on areas like the chest, back, shoulders, or face.

Shingles is a skin disease that results in a rash of fluid-filled blisters. It's caused by the same virus that causes chickenpox, known as the varicella-zoster (vair-ee-SEHL-uh ZAWS-tuhr) virus.

Skin cancer is the most common cancer in America, but it's also the most curable when treated early. There are three general types, listed in order of increasing seriousness: basal cell carcinoma (BAY-suhl car-sih-NOH-muh), squamous (SKWAY-muhs) cell carcinoma, and malignant melanoma (mel-uh-NOH-muh).

Tinea versicolor (TIHN-ee-ah VER-sih-cuhl-or) is a mild fungal infection caused by yeast that's present on everyone's skin. In some individuals, however, this yeast overgrows, causing discolored spots ranging from pale pink to tan to dark brown on darker skin.

Vitiligo (viht-ih-LYE-goh) is a skin disorder in which pigmentation is lost, leading to patches of completely white skin. Body hair in that region may also turn white.

Warts are non-cancerous growths on the skin that may be caused by over 70 different viruses known as human papillomaviruses (pap-ih-LOE-muh-VY-rih-suhz), or HPV (H-P-V).

Normally, your immune system defends your body against bacteria, viruses, and other invaders by producing antibodies and special white blood cells which attack these foreign organisms.