Psoriasis is a chronic, non-contagious inflammatory disease of the skin characterized by red patches covered with silvery scales. It most commonly affects the elbows, knees, scalp, back and torso. Factors like genetics, infections, stress, and certain medications can trigger flare-ups. Treatment involves topical creams and ointments, phototherapy using UV light, or systemic medications in severe cases. Managing stress and keeping skin moisturized can also help control symptoms.