Protecting yourself from UVA and UVB radiation is very important during these hot sunny summer months. UVB rays are the rays responsible for tans and sunburns. UVA rays are sneakier because they don't cause reddening but do contribute to cell damage and aging. SPF (sun protection factor) of sunscreens only measure your protection from UVB rays. Zinc oxide is considered one of the better protectors against UVA rays. The SPF tells you how much longer you can stay out in the sun without getting burned. So, if you apply SPF 10 before going outside, you can in theory stay out 10 times longer before burning. If you normally begin to get pinkish or red after say 15 minutes, then SPF 10 allows you 150 minutes of exposure before reddening. This is not a perfect system, however, and depends somewhat upon your skin type, the amount applied, frequency of re-application, activities which might involve sweating or rubbing the sunscreen off, and the time of day/angle of exposure.
In addition to skin cancer concerns, the sun is responsible for many signs of aging, and protecting your skin from its rays helps keep your skin looking younger. Some foundations and facial moisturizers contain sunscreen to help you protect your face daily. I have very fair skin, so in addition to makeup with SPF 15, I also apply a separate sunscreen to my face daily. In the summer, I also apply sunscreen to my arms daily as part of my morning routine. This has helped me on many occasions when I ended up out in the sun longer than anticipated.
Tanning yourself does not give you a "healthy glow", it is a sign of sun damage. Glowing skin comes from taking good care of your skin, and also your "inner glow" shining through! If you are blessed with naturally darker skin, your natural skin color provides a little more protection. For those of us with lighter skin...protect your skin and stay out of the tanning beds! Pale (think porcelain or dewy) can be beautiful, too.