Abstract: This review describes the basic and application aspects of the optical properties of nanoparticles (NPs), which determine the dynamics and results of optical (laser) radiation interaction with NPs and their surroundings through NP light absorption and heat generation. In addition to the importance of primary optical processes, the thermal application of the light–NP interaction has attracted significant interest from various areas ranging from photochemistry to laser material processing and nanobiomedicine. First of all, the information provided is intended for laser specialists, photochemists and nanobiologists who are not so familiar with various optical data for understanding of the influence of NP optical properties on the results of optical or laser action on NPs and medium. Secondly, our review will be useful for researchers who conduct high-temperature investigations of the intense optical action on NPs that needs to take into account the dependence of NP optical properties on its temperature under NP heating. Our attention is focused on two variants of the applications of NP optical properties. Firstly, we shortly reviewed the optical properties of NPs at their initial or slightly higher temperatures reached under the influence of moderate radiation intensity. They are presented in numerous publications and are used as basic data. On the other side, the development of modern high-temperature laser and optical technologies needs to use the NPs optical properties at temperatures of about 1x103 K and more. For high power laser and optical technologies, it is necessary to take into account the temperature dependences of the optical parameters of various metals, dielectrics and other materials. Among these technologies, one should list laser processing of NPs, thermal laser biomedicine, solar and photo nanocatalysis, solar nanostructured absorbers. The selection and use of suitable optical properties of NPs are crucial to successful achievements and results in high-temperature experiments and applications. Novel information on optical property dependence on temperature obtained from currently available literature has been presented for possible applications in optical and laser high-temperature processes interactions with NPs. However, unfortunately, the essential information on the effect of temperature on the optical properties of NPs is currently limited. In addition to the latest information, this review also includes the figures obtained by our own calculations to provide readers with a better understanding of the NP optical properties. From the side of the application, the use of NP optical properties is considered, which provide multiple varieties of moderate and high-temperature technology opportunities, many of which are ongoing and some of them are promising bright results in the near future. The beneficial outcome and the results of further activities in the research of intense laser and optical interactions with NPs can influence various fields of science and technology: nano and photochemistry, biomedicine, nanophysics, material science, etc.