Epididymitis is an inflammatory condition of the epididymis, a structure behind the testes that stores sperm. It is commonly caused by sexually transmitted infections in younger men. Symptoms include painful swelling of the epididymis and testicles. Diagnosis involves fluid and urine tests. Treatment focuses on antibiotics and pain relief, while severe cases may require surgery to remove infected tissue. Complications can include abscesses, infertility, and testicular tissue death if not properly treated.