Psoriasis is an immune mediated disease. It involves skin but it has many other effects on internal organs. In psoriasis, reddish plaque occurs in skin & covered & scale. Psoriasis can involve in small part of body skin but it can also spread all over the body. Psoriasis is not a curable disease but can be controlled in a good shape. Psoriasis is not a contagious disease. Treatment of psoriasis depends on the involvement of skin & area of the skin.