Life on earth depends on the solar energy which is fixed in the biosphere by photosynthesis in plants which have pigments that harvest sunlight. Thus, plants are constantly also exposed to ultraviolet irradiation. In plants wide inter- and intraspecific differences have been reported in response to UV radiation with respect to growth, production of dry matter and biochemical changes. The direct effects of UV radiations on plant cells are mostly damaging, because UV photons have enough energy to create lesions in important UV-absorbing biomolecules. Also, the present work ascertains that plants employ strategies of protection to counter the detrimental effects of visible light and UV radiation absorption. In spite of being much information available on the influence of either UV-B radiation or visible light intensity on plant tissues, yet no appropriate information is available on the influence of UV-C and UV-A. This monograph is to provide students having diverse backgrounds and interests with a clear insight into the present state of our knowledge in the subject, and to highlight the problem areas where current research effort is either located or needed.