Erectile dysfunction is defined as the inability to attain or maintain an erection firm enough for sexual activity. It affects over half of men between 40-70 years old and around 25% of men over 65. The condition results from insufficient blood flow into the penis during sexual stimulation, which is regulated by the parasympathetic nervous system releasing nitric oxide. Potential causes include various physical health problems, psychological factors like anxiety, as well as lifestyle risks like smoking or lack of exercise. Treatment involves oral medications like sildenafil, counseling, medical devices, injections, or implants depending on the underlying cause and severity.