Although atopic dermatitis (AD) is the most common skin disorder, there remains an ongoing debate on this denomination, its definition and the binary view based on immunoglobulin E measurement. The wide spectrum of the clinical phenotype of AD reflects the complex genetic and pathophysiologic mechanisms underlying the disease. The diagnostic criteria have to be reconsidered and adapted to different ethnic populations. There is an urgent need for biomarker discovery further supporting the clinical diagnostic criteria as well as the precision medicine approach on a global level.