This article summarizes and updates a number of issues related to hydrocele including anatomy, embryology, classification, etiology, clinical manifestations, imaging findings, and management. Hydrocele is an abnormal collection of serous fluid between the parietal and visceral layers arising from the mesothelial lining of the tunica vaginalis that surrounds the testis and spermatic cord directly. Hydroceles result from an imbalance of secretion and reabsorption of fluid from the tunica vaginalis. Hydroceles can be divided into two types as primary and secondary. The diagnosis should be based on medical history, clinical manifestations, and imaging studies. Understanding the causes and types of hydroceles is useful for accurately diagnosing and treatment strategy. Hydroceles can be managed by conservative treatment, fluid aspiration, or hydrocelectomy.