Eczema is the most common form of dermatitis – it’s sometimes known as atopic dermatitis when it becomes a chronic skin condition.
It causes an inflammation of the skin possibly accompanied by redness, rash, or blisters. Long term eczema can also cause a thickening of the skin.
The most important (first aid) treatment for eczema is hydration of the skin, not with water but deep-penetrating creams.