Molecular photoswitches , molecules that undergo structural changes upon optical stimuli, enable scientists to remotely control the motion of molecules and to modulate their properties and functions. These compounds attract considerable attention, as they play significant roles in various fields ranging from nanotechnology to biology , and their great potential has been shown in applications such as data storage , drug delivery , sensing , catalysis , and energy conversion, etc. Over the past decades, various types of photoswitches have been developed and explored, including azobenzenes , diarylethenes , and spiropyrans , and hydrazones . Among these photochromic compounds, hydrazone-based switches , which are a new addition to the molecular toolbox available to the community, uniquely combine ease of synthesis, bistability (thermal half-life as long as 5300 years ), fatigue resistance, mutli-phase switchability in an easily accessible and modular structural framework. Our recent systematic structure-property study using a family of hydrazone switches has shown that their properties, including activation wavelengths, photostationary states (PSSs), quantum yield, thermal half-lives, and solution/solid-state fluorescence characteristics, are highly dependent on the electronic property of the substituent groups of the hydrazone. Optimization of these properties will pave avenues to opportunities for developing new applications and thus greatly enhances the proliferation of hydrazone switches as effective tools in various research fields.