A sunscreen is a product that helps prevent then suns ultraviolet radiation from getting to the skin and damaging it.
LITTLE FACT: it actually takes 20 minutes for your unprotected skin to start turning red, using a sunscreen theoretically prevents reddening 15 times longer.
To get a little bit more into what ultraviolet radiation is a form of electromagnetic radiation and the sun is the main source, and tanning beds also have them, so you are not safe snooki!
There are 2 types of UV:
- UVA: this is the one that penetrates the skin more deeply damaging skin cells. this kind of rays penetrate clouds and glass, they are the dominate tanning rays, and the biggest responsible in photoaging.
Did you know that when tanning the skin turns darker trying to protect itself from further DNA damage?
- UVB: it causes skin reddening and sunburns. it damages the skin superficially, the snow, ice, water anything that is reflective bounces 80% of rays, which basically means that it kits the skin twice (when coming down, and then going back up)
you should be applying sunscreen everyday, and believe me I forget it too, but since i have done a lot of research for this, i started applying it, like crazy, to my skin.
you should apply sunscreen at least 15 before applying anything else to the skin, but the timing is yours, it depends on how long your skin takes to absorb a product.
You have to re apply your sunscreen, specially when you are underwater, it doesn't matter if they are waterproof.
So, honestly sunscreen should be IMPORTANT in your everyday routine, because you can prevent a lot, like wrinkles, cancer, dark spots, and many other things.
BTW: titanium dioxide and zinc oxide are the active products on sunscreen that are supposed to cause the white cast you get she you take pictures, but i believe it can just be the mica products that your using.