By Erika Owen
August 25, 2016
Credit: Getty Images

We all use it (or should be): sunscreen. It helps prevent painful sunburns by protecting our skin from the sun's harmful rays.

At its most basic, sunscreen is a lotion or cream we rub all over our bodies to prepare for an afternoon of sun. What that lotion is really comprised of are chemical compounds that naturally deflect ultra-violet (UV) rays.

But there are many misunderstandings about wearing sunscreen: Are the higher SPFs better for me? What does SPF even mean? We're hear to clear the air around this everyday staple.

Types of sunscreen

As How Stuff Works explains, there are two different kinds of sunscreen: physical formulas (which reflect sunlight) and chemical sunscreens (which absorb UV light). There are pros and cons to both.

Physical sunscreens protect you from both UVA and UVB rays and starts working the minute it is applied. It also lasts longer if you're in direct sunlight. But steer clear if you're going to be doing any swimming, because it will rub off. It's also thicker and can cause you to sweat more than usual.

Chemical sunscreen is thinner and easier to apply equally, which can be tough to do. (There's even a special gadget for even sunscreen application.) It requires about 20 minutes before it starts to work. With chemical sunscreens, the higher the SPF (more on what that actually means later), the more risk there is for skin irritation.

SPF, defined

This is one of those acronyms that is tossed around so much, it's easy to miss what it actually means.

SPF stands for Sun Protection Factor, or how likely the product is to protect you from harmful rays, as explained by Consumer Reports. The number refers to how much longer than you stay in direct sunlight than if you weren't wearing sunscreen.

For example, if you're wearing SPF 15, you can safely enjoy a particularly sunny day 15 times longer than you could if you were wearing no sunscreen at all. Another way to think about it: The number refers to the fraction of harmful rays that are making their way to your skin, so SPF 15 would mean you're being exposed to 1/15 of the rays you would be subjected to had you forgotten the sunscreen.

Is a higher SPF better for you?

SPF is really only responsible for protecting you from the rays that cause sunburns (UVB rays), as opposed to UVA rays, which are more known for skin damage.

It's easy to mistake SPF 30 as being twice as strong as SPF 15 and SPF 60 as the formula for the most fragile of skin types, but that's not how it works. According to WebMD, the number really refers to how long you can spend under the sun before suffering damage, i.e. a nasty sunburn. No sunscreen offers 100 percent protection from UVA and UVB rays.

For more information on the right way to wear your sunscreen, head over to the Centers for Disease Control and Prevention.
