So-called young skin is skin whose cell renewal is very rapid, therefore every 21 days. However, over the years, this renewal slows down due to several factors:

• the individual biological clock;
• the stress;
• the lifestyle;
• skin maintenance;
• the environment.

This is when the process of premature aging begins. We see the appearance of expression lines and often superficial dehydration. From the age of 25, the skin loses 5 % of its collagen each year. The first wrinkles will appear slowly over the years.