Thanks to technology and all that we know about aging today, firm and glowing skin isn't something you have to leave behind in your youth.

Each decade of our lives brings with it new skin issues and conditions. But if you know how to give your skin exactly what it needs to function smoothly, you can enjoy the rewards of great skin throughout your life.

"The difference between 20s, 30s, 40s and 50s varies depending on where you live and what season it is," says Mount Kisco, N.Y., dermatologist Dr. David Bank.

For example, skin plumpness may be better preserved in warmer, more humid climates, while dry and cold conditions can cause fine lines to peek out earlier than they otherwise would. Yet regardless of where you live, there's one skin fact that holds true.

"The most evident change is that skin is getting drier from your 20s on," says Bank.

That change in physiology means different things for different decades of your life. We've asked a couple of the country's leading dermatologists to explain what you should be looking for, how you should be treating your skin, and optional products and treatments that can maximize your results at every age.

And a word of advice to those who are on a tight budget or just prefer to play it simple -- one essential product still does more by way of prevention than anything else.

"If you must stick to one beauty product, I would definitely recommend sunscreen," advises Bank, who also suggests that acne-prone skin types read product labels closely to make sure they purchase a version that doesn't contain any oils.

With sunscreen in hand -- SPF 20 or more is the general recommended strength -- click through the photo gallery above for a tour of how to keep beautiful skin at every age.

And check out these 4 tips to look and feel more beautiful at any age.