Characteristics of skin types
1. Normal skin (Eudermic skin)
What is it?
Normal skin has a balanced sebum production and moisture level. The hydrolipid barrier is intact, which keeps the skin well hydrated and resistant to external influences.
Features:
- Fine pores and an even skin texture
- No excessive greasiness or dryness
- Little to no impurities
- Good blood circulation, healthy and radiant complexion
2. Acne (Acne vulgaris)
What is it? 
An inflammatory skin condition caused by excess sebum production, clogged pores, bacterial infections ( Cutibacterium acnes ), and inflammatory responses.
Features:
- Presence of pimples, blackheads (comedones), papules and pustules
- Often oily skin with visible pores
- May cause scarring or post-inflammatory hyperpigmentation
- Usually occurs on the face, chest and back
3. Dry skin (Xerosis cutis) 
What is it?
A skin that produces insufficient sebum and natural moisture-retaining substances, leading to a reduced skin barrier and increased sensitivity to external factors.
Features:
- Feels rough, tight and sometimes flaky
- Fine lines visible, especially around the eyes and mouth
- May show itching and redness
- Sensitive to temperature fluctuations and irritants
4. Pigmentation (Hyperpigmentation & Hypopigmentation) 
What is it?
A disruption in the skin's melanin production, resulting in darker (hyperpigmentation) or lighter (hypopigmentation) spots. Hyperpigmentation can be caused by UV damage, hormonal fluctuations (melasma), or inflammation.
Features:
- Darker or lighter discolorations on the skin
- Can be caused by sun damage, acne scars, hormonal changes or skin lesions
- Usually visible on the face, hands and other sun-exposed areas
5. Wrinkles (Rhytides and Elastosis cutis) 
What is it?
A loss of collagen, elastin and hyaluronic acid in the skin, resulting in reduced firmness and elasticity. This process is accelerated by UV radiation (photoaging), smoking and oxidative stress.
Features:
- Fine lines and deep wrinkles, especially around the eyes, mouth and forehead
- Sagging skin and loss of volume
- Dry skin and reduced resilience
- Can be aggravated by a lack of hydration and antioxidants
6. Rosacea 
What is it?
A chronic inflammatory skin condition characterized by redness and visible blood vessels on the face. The exact cause is unknown, but genetic and environmental factors play a role.
Features:
- Redness (erythema), especially on the cheeks, nose, chin and forehead
- Sometimes visible broken capillaries (telangiectasias)
- May be accompanied by a burning sensation and sensitivity
- In some cases development of bumps or pimples
7. Blackheads (Comedones) 
What is it?
Accumulation of sebum and dead skin cells in the pores. Blackheads (open comedones) darken due to oxidation of sebum, while whiteheads (closed comedones) remain under the skin surface.
Features:
- Small black or white dots, especially on the nose, chin and forehead
- Common in oily or acne-prone skin
- Not inflamed, but can develop into pimples if infected
8. Combination skin 
What is it?
A skin type in which some areas (usually the T-zone: forehead, nose and chin) are oily, while other areas (such as the cheeks) are dry or normal.
Features:
- Shiny and oily areas on the forehead, nose and chin
- Dry or normal cheeks
- Sometimes enlarged pores in the T-zone
- May be sensitive to skin care products
9. Sensitive skin 
What is it?
Skin that overreacts to external factors, such as skin care products, temperature changes or allergens. The skin barrier is often weakened, causing irritations and inflammations to occur more quickly.
Features:
- Redness, itching and a burning sensation
- Rapid response to cosmetic ingredients or weather conditions
- Dryness and a tight feeling
- Tendency to inflammation and flaking
10. Dehydrated skin (Skin dehydration)
What is it?
A temporary condition in which the skin does not retain sufficient moisture, often due to a disrupted skin barrier or a deficiency of hydrating substances such as hyaluronic acid.
Features:
- Tight feeling, especially after cleansing
- Dull complexion and fine dryness lines
- May be accompanied by flaking and increased sensitivity
- Can occur on all skin types, including oily skin
These scientific descriptions help identify skin types and choose the right skin care routine.