Freckles

• Freckles are usually friendly, small tan or light brown spots on sun-exposed skin.
• Freckles can be mistaken for moles and other skin growths.
• Freckles themselves are quite harmless and rarely develop into skin cancer.
• Freckles can be confused with more serious skin problems.
• Skin cancer can at times masquerade or hide as a freckle.
• Uncertain colored or pigmented spots should be examined by your physician or dermatologist.
• Effective treatments are available to help lighten or eliminate bothersome freckles.

Freckles are flat, tanned circular spots that typically are the size of the head of a common nail. The spots are multiple and may develop randomly on the skin, especially after repeated exposure to sunlight. These are particularly common in people of fair complexion on upper-body skin areas like the cheeks, nose, arms, and upper shoulders. They may appear on people as young as 1 or 2 years of age.

Most freckles on a person's skin are usually uniform in color. On different people, freckles may vary somewhat in color -- they may be reddish, yellow, tan, light brown, brown, or black -- but they are basically slightly darker than the surrounding skin. They tend to become darker and more apparent after sun exposure and lighten in the winter months. Freckles are due to an increase in the amount of dark pigment called melanin and are not due to an increase in the total number of pigment-producing cells called melanocytes. The word freckle comes from the Middle English freken, which, in turn, came from the Old Norse freknur, meaning "freckled." (Some speakers of Old English and Old Norse must have had a tendency to developing freckles.)

Source: MedicineNet.com
http://www.medicinenet.com/freckles/article.htm