Sunscreen Vs. Sunblock - What's the Difference?

When people talk about physical sunblock and chemical sunscreens, I don't understand how they are different.  Which one works better? 

2 doctor answers

What's the Best Sunscreen?

Hope you can give me tips on what are the most effective sunscreens.  Sunscreens are expensive so your help is very appreciated.

3 doctor answers

Is There Baby Sunscreen?

Is there baby sunscreen? What sun protection for my baby should I follow?

Should I Get a Base Tan Before Vacation?

Do the benefits of getting a base tan (via tanning bed) before a sun-filled vacation outweigh the general risks of tanning?