PURPOSE: Neutropenia is a hematologic condition characterized by an absolute neutrophil count < 1500/μL, associated with increased infection risk. This review aimed to provide an updated overview of the classification, pathophysiology, etiology, diagnosis, and management of neutropenia in congenital and acquired forms. METHODS: We conducted a comprehensive literature review of various causes of neutropenia, including genetic syndromes, autoimmune disorders, infections, and drug-induced mechanisms. Emphasis was placed on clinical manifestations, underlying mechanisms, diagnostic algorithms, and therapeutic approaches, including recent advances in molecular diagnostics and biologic therapies. RESULTS: Neutropenia can result from decreased neutrophil production, immune-mediated destruction, or abnormal distribution. Congenital neutropenia is often linked to mutations in genes such as ELANE, HAX1, and SBDS. Acquired neutropenia can be caused by chemotherapy, infections, autoimmune diseases, or nutritional deficiencies. Diagnostic evaluation requires a stepwise approach incorporating clinical history, blood counts, peripheral smear, bone marrow biopsy, and molecular or serologic testing. Treatment depends on the etiology and severity and includes granulocyte colony-stimulating factor, immunosuppressants, antimicrobial prophylaxis, and hematopoietic stem cell transplantation in selected cases. CONCLUSION: Neutropenia is a multifactorial disorder requiring individualized evaluation and management. Advances in genetic and immunological diagnostics combined with targeted therapies have improved risk stratification and outcomes. Early recognition and a multidisciplinary approach are essential to reduce infection-related morbidity and prevent progression to hematologic malignancies in high-risk patients.