If you like spending time outdoors, it's important to protect your skin from the sun, so you can avoid painful sunburns.

"Sunburn results when the amount of exposure to the sun or other ultraviolet light source exceeds the ability of melanin to protect the skin," according to University of Florida Health. "Melanin is the skin's protective coloring (pigment). Sunburn in a very light-skinned person may occur in less than 15 minutes of midday sun exposure, while a dark-skinned person may tolerate the same exposure for hours."

The best way to prevent a sunburn is to limit the amount of time you spend in the sun, especially between about 10 a.m. and 4 p.m. The next best prevention, no matter the time of day, is to use sunscreen.

Sunscreen protection

Sunscreen is rated based on its ability to protect your skin from ultraviolet A and ultraviolet B rays. Only broad-spectrum sunscreens protect you from UVA rays, which cause aging and cancer. All sunscreens protect your skin from UVB rays, which cause sunburn.

In addition to looking for a broad-spectrum sunscreen, pay attention to the sun protection factor, usually called SPF, which determines the quality of a sunscreen and how much protection it offers.

"There's a certain number that comes with that SPF factor, and it tells us how long that it takes to get a sunburn while you're wearing that sunscreen," said Savannah Ray, physician assistant with Gardens Dermatology & Cosmetic Surgery Center. "So, the higher number, the more protection you have and the longer you have until you get a sunburn while wearing that sunscreen."

For example, using a sunscreen with an SPF of 30 would extend the time it takes you to burn to 30 times longer than when you're wearing no sunscreen. SPF is also an indicator of what percent of UVB rays are blocked.

Sunscreen application

The protection provided by sunscreen is only as good as its application, so make sure every inch of skin is covered about 30 minutes before going outside, and reapply every two hours. If you'll be getting wet, plan on using a water-resistant sunscreen and reapplying immediately after swimming or sweating.

Chemical and physical sunscreens

Another aspect to keep in mind is that the ingredients in chemical sunscreens differ from the ingredients in physical sunscreens.

"The chemical sunscreens absorb the rays and convert them into energy, while the physical sunblocks reflect and scatter the rays," Ray said. "Physical sunblocks are preferred by a lot of patients because they can be a little less irritating, and they can be a little bit easier to put on."

A dermatologist can help you choose the right type of sunscreen for your skin.

"We can look and evaluate your specific skin type and tone and talk about your activity and your lifestyle and find the right sunscreen that fits for you," Ray said.