What is the difference between UVA and UVB rays?

My every day face lotion has SPF in it. Is it safe to just use this before i go to the beach?

What is SPF?

How do i know what SPF i need?

If i apply a lotion with an spf 8 and then put an spf 15 on top of it, does that mean i’m actually wearing an spf 23?

I’ve heard that you don’t need more than spf 15. Is that true?

Why do some people tan and others burn?

What questions about skin type should i consider when choosing sun protection?

Do you burn moderately and tan gradually?

If i am fair-skinned, can i tan at all?

Do i need to take extra precautions in the sun if i’m taking medication?

I was fine when i left the beach, so why am i burnt now?