Unique structural features of metal-organic frameworks such as their organic-inorganic nature, coupled with a series of weak and strong chemical interactions, provide these hierarchical materials with an adaptive response to external stimuli (including light). The latter allows one to demonstrate energy-efficient and ultra-fast optical processes for light generation, conversion, triggering, encryption, absorption, and transition. Covering the current state and perspectives in this new field of material science for photonics, the report aims to develop a deep understanding of the interaction of light with such hierarchical materials to create sustainable and energy efficient optical devices.