Psoriasis is a chronic autoimmune skin disease that causes red, scaly patches to form on the skin, most commonly on the elbows, knees, scalp, and trunk. It is characterized by inflamed, itchy, and sometimes painful plaques due to an overactive immune system that accelerates skin cell growth. While there is no cure, treatments like topical creams, phototherapy, and systemic medications can help manage symptoms and control flare-ups, which can be triggered by factors such as infections stress, and certain medications.