<p>Atopic dermatitis (AD) is a highly prevalent, chronic inflammatory skin disease that predominantly begins in early childhood. Increasing evidence supports that pediatric AD is not a single entity, but rather a spectrum of overlapping phenotypes and endotypes, defined by clinical presentation, immune profile, genetics, ethnicity, and comorbid atopic conditions. This review provides a comprehensive synthesis of current knowledge on childhood AD heterogeneity, emphasizing severity, age of onset, allergen sensitization, allergic comorbidities, ethnicity, and disease trajectory. Phenotypic classification - based on clinical severity, lesion distribution, and disease course - offers valuable prognostic insight, particularly in relation to the risk of asthma, allergic rhinitis, food allergy and eosinophilic esophagitis. Endotyping approaches, including transcriptomic, proteomic, lipidomics, metabolomics and cellular analyses, have revealed distinct immune signatures across age and ethnic groups, including Th2-predominant, Th17/Th22-skewed, or mixed inflammatory pathways. Ethnic-specific differences, such as Th17 activation in Asian populations or Th2/Th22 predominance in individuals of African ancestry, further underscore the need for tailored therapeutic strategies. The emergence of multiomics and clustering-based approaches has begun to identify molecular subgroups, although challenges remain in standardizing methods and validating findings across diverse cohorts. Importantly, the identification of biomarkers to predict disease trajectory and treatment response is a critical unmet need. Future research should prioritize longitudinal, multiethnic, and integrative studies to refine endotyping, enable early intervention, and guide precision medicine in pediatric AD. Understanding the dynamic interplay between genetics, immune dysregulation, and environment will be key to unlocking improved outcomes for children affected by this complex disease.</p>