Heimig, ConnorConnorHeimigBaù, EnricoEnricoBaùBiechteler, JonasJonasBiechtelerLee, YohanYohanLeeAntonov, Alexander A.Alexander A.AntonovTittl, AndreasAndreasTittl2026-10-202026-10-202026-10-05Nature Reviews Materials (in Press): (2026)https://hdl.handle.net/11420/65376Metasurfaces are planar, ultrathin arrays of subwavelength nanostructures that provide unprecedented control over optical fields. Initially demonstrated for wavefront shaping in beam steering and holography, metasurfaces are now recognized as a versatile platform for engineering light–matter interactions over broad spectral ranges. This Review surveys how the synergy between structured geometries and material excitations enables metasurfaces to act as a common photonic framework for concentrating light into deeply subwavelength volumes, substantially amplifying optical emission, interaction strengths and nonlinear responses, and giving rise to hybrid light–matter states known as polaritons. We first provide a comprehensive overview of relevant resonance mechanisms and coupling regimes before describing the predominant material excitations (plasmonic, excitonic and phononic). For each, we highlight unifying design principles, the resulting diversity of physical phenomena and the fundamental opportunities and limitations posed by metasurface integration. We close by outlining emergent directions and opportunities for the field, including tailored symmetries as well as topological and quantum metasurfaces.en2058-84372026Nature Publishing GroupNatural Sciences and Mathematics::530: PhysicsJournal Article10.1038/s41578-026-00951-1