Freckles, also known as ephelides, are flat, tanned and concentrated clusters of the pigment melanin found on the skin. The vast majority of the time, freckles are completely benign and are not associated with any other sort of systemic illness
. Freckles tend to be brought out by exposure to the sunlight, which is why they most often are found on the face, shoulders, upper back and arms. They do not contain melanin-producing cells, also known as melanocytes, which is the major difference that separates them from moles. As freckles do not contain any cells, they are at no risk of transforming into something dangerous. Moles, or nevi, on the other hand, are composed of cells. These collections of cells can appear anywhere on the body, and may look very different from each other depending on where the cells proliferate (i.e. some form on top of the skin while others form between different layers within the skin). Because moles are composed of cells, they are also at risk of developing into something dangerous, such as melanoma. For this reason, it is very important to protect against the development of moles (through sun protection) and to keep a very close eye out for changes to any pre-existing moles. For any changes in the characteristics of a mole, a dermatologist
should be consulted.