The workings of nanomaterials used in sunblocks, tumor-killing nanoshells, and as catalysts are described step-by-step on a high level. All genuine nanomaterials are 100nm or less in at least one dimension. The diameter of the soccer ball-shaped fullerene molecule can be under a nanometer. The carbon nanotube can have a like diameter, but may be thousands of namometers in length. In sunblock, particles of zinc oxide or titanium dioxide are mixed into their formulas because the particles block-skin-damaging ultraviolet light, but because they also reflect visible light, the sunblock appears as a white ointment. Nanoparticles also block UV light, but not larger visible light waves. The ointment appears clear but still guards skin. To kill tumors, gold nanoshells begin with a nanoscale silica core. Gold gathers around the core to form a shell. Nanoshells with a particular core-shell ratio absorb near infra-red light, which passes through tissue without damaging it. For cancer detection and eradication, researches add antibodies or proteins to the shell that attach onto cancer cells. Shells attach on the tumor surface. A blast of near-infrared light penetrates flesh and is absorbed by the shells. The shells heat up to kill cancer cells, but not healthy tissue. Catalysts can be made only a few nanometers deep, which means large cost reductions, because they provide needed surface without bulk. Also highlighted is the fact that some nanomaterials have to be made over before they can be used in specific applications.