A hydrocele is a fluid-filled sac surrounding the testicle, leading to scrotal swelling. It commonly occurs in newborns due to fluid accumulation during development, often resolving on its own within the first year. In adults, hydroceles may develop due to injury, infection, or inflammation in the scrotum, or as a result of underlying conditions like varicocele or orchitis. Symptoms include painless swelling, discomfort, or heaviness in the scrotum. Diagnosis involves physical examination and sometimes ultrasound. Treatment may not be necessary if the hydrocele is small or asymptomatic, but surgery to drain or remove the fluid may be required in some cases.