Abstract: Metasurfaces provide an ultrathin and highly designable platform for optical field manipulation. Early studies primarily relied on the local scattering responses of subwavelength meta-atoms, enabling point-by-point modulation of the phase, amplitude, and polarization of light in real space and thereby driving the rapid development of planar optical devices. In recent years, with the introduction of physical mechanisms such as guided-mode resonances and bound states in the continuum, metasurfaces have progressively acquired nonlocal degrees of freedom, thereby exhibiting pronounced wavevector-dependent characteristics in momentum space. Within this emerging framework, light-field manipulation has been extended from purely local response design to the holistic engineering of spatial-frequency components and delocalized modes, enabling functionalities that are difficult or impossible to achieve with conventional local metasurfaces, including spatial differentiation, lateral energy transport, and multifunctional optical-field control. A systematic examination of the physical implications and implementation pathways of local responses and nonlocal degrees of freedom, together with their intrinsic distinctions and cooperative interplay, is therefore essential for deepening our understanding of metasurface-based light-field control mechanisms and for providing a solid physical foundation for the development of next-generation planar optical devices.