Abstract: Structural colors refer to colors arising from the scattering and interference of light by judiciously designed nanostructures. To be viable candidates for display or smart colorimetric sensing applications, their responses must be dynamic. To this end, our lab has worked on designs that can be tuned through a suite of external stimuli including electricity, humidity, and chemical vapor. Unlike plasmonic designs that require the excitation of surface plasmons, our approach mainly relies on photonic responses such as Mie resonances and dielectric waveguide-array modes which free our system from ohmic damping and the interdependence between wavelength and intensity. We also extend our approach to the microwave regime where unprecedentedly thin electromagnetic wave absorbers are realized.