If you have freckles, you've probably noticed that a long day in the sun makes them far more prominent. Why is that? Well, to understand why it happens, you'll have to understand where freckles come from in the first place.

We all have cells in our skin called melanocytes. These specialized cells are designed to protect us from the harmful ultraviolet rays of the sun. They do so by producing a pigmented protein called melanin. Melanin acts like a pair of sunglasses for your skin by making it darker. In many people, these melanocytes are spread out evenly throughout the body, but in others they aren't. They get bunched up together, resulting in freckles.

If your melanocytes are spread out evenly and you spend some time in the sun without sunblock, you'll probably end up with a nice, even tan as your melanocytes produce pigment to protect you. But if your melanocytes are bunched together, sun exposure will lead to scattered, dark spots -- freckles. And since parts of your skin aren't getting more pigment, you'll probably have a sunburn, too.

Some people who didn't have freckles as children eventually develop them through repeated sun exposure. Hands and faces -- which tend to get the most sun -- are the areas where freckles are most likely to develop. If you want to prevent freckles, you should wear a good sunscreen and limit your exposure to the sun or any other sources of ultraviolet rays, like tanning booths.

Unfortunately, people with freckles are also at a higher risk for skin cancer. While freckles themselves are harmless, you should always keep an eye on them. If you notice unusual changes in your freckles, contact a medical professional.

Visit the next page to find more information on why freckles come out in the sun.