Among the numerous skin classifications that are proposed, the one most closely connected with cosmetological requirements distinguishes four different types: ormal, oily, dry, and mixed.
However, in practice, such a classification must be used cautiously. In fact, the words
used are ambiguous and lead to various interpretations; the criteria of selection to define each category are difficult to standardize since they vary from one case to another, some observations can even correspond to opposite clinical profiles.
So, for example, severe changes in epidermal water content associated with superficial pH changes can modify the skin’s appearance and lead one to establish a visual diagnosis of dry skin, whereas it may be actually an oily skin.