Sunscreens protect the skin. They help block ultraviolet (UV) radiation from being absorbed by the skin. UV radiation damages the skin and can lead to sunburns and skin cancer. No sunscreen blocks UV radiation 100%. But they allow you to be outdoors for a longer time before your skin starts to redden. Using sunscreen doesn't mean you can stay out in the sun for an unlimited amount of time. Damage to your skin cells is still happening.

Most skin cancers are caused by too much exposure to UV rays. The sun protection factor (SPF) on a sunscreen label shows how well the sunscreen protects against UV rays. Higher SPF numbers mean more protection from UV rays. But no sunscreen can block all UV rays.

A sunscreen protects from sunburn and reduces suntan by absorbing or reflecting UV rays. Selecting a good sunscreen is important for protecting the skin. Choose a sunscreen that has:

• Broad-spectrum protection. This protects against both UVA and UVB rays.
• An SPF of 30 or higher
• Water resistance, or is waterproof. This means the sunscreen protects while swimming or sweating for a certain amount of time—either 40 or 80 minutes, depending on the label.

The best type of sunscreen is the one that offers the benefits above. The type or brand you use is your choice. Sunscreen is available in lotions, creams, gels, ointments, wax sticks, and sprays. Just be aware that different sunscreens contain different ingredients. Stay away from products that have ingredients that can irritate your skin.

Even when people use sunscreen, they often don't apply enough of it or don't apply it correctly. This limits how useful it is. Follow these guidelines:

• Apply sunscreen to all areas of skin that won't be covered by clothing.
• Use at least 1 ounce of sunscreen (enough to fill a shot glass) to cover exposed areas. An ounce should cover the whole body. But you might need to adjust the amount depending on your body size and body hair.
• Apply the sunscreen to dry skin about 15 to 30 minutes before going outdoors. This gives it time to be absorbed.
• Reapply sunscreen at least every 2 hours, or more often after swimming or sweating.
• Protect your lips by applying a lip balm or lipstick that contains sunscreen with an SPF of 30 or higher.

Remember that children need protection from the sun, too. Sunscreens are recommended for everyone over 6 months of age. For babies younger than 6 months, the American Academy of Pediatrics approves of the use of sunscreen only if adequate clothing and shade are not available. Parents should still try to keep young babies away from sun exposure, especially out of direct sunlight. Dress a baby in lightweight clothing that covers most surface areas of skin. Parents also may apply a small amount of sunscreen to exposed areas, such as baby's face and back of the hands.

Using sunscreen when you're going out in the sun is important. But it is only one part of an overall plan to protect your skin from harmful UV rays. Other important ways to protect your skin include:

• Seek shade when appropriate. Limit your sun exposure between 10 a.m. and 4 p.m., when UV rays are the strongest.
• Wear a hat with a wide brim and tightly woven clothing that covers most of your skin, as well as sunglasses.
• Don't use tanning beds or sunlamps.