  Our ability to generate new distributions of light has been remarkably
enhanced in recent years. At the most fundamental level, these light patterns
are obtained by ingeniously combining different electromagnetic modes.
Interestingly, the modal superposition occurs in the spatial, temporal as well
as spatio-temporal domain. This generalized concept of structured light is
being applied across the entire spectrum of optics: generating classical and
quantum states of light, harnessing linear and nonlinear light-matter
interactions, and advancing applications in microscopy, spectroscopy,
holography, communication, and synchronization. This Roadmap highlights the
common roots of these different techniques and thus establishes links between
research areas that complement each other seamlessly. We provide an overview of
all these areas, their backgrounds, current research, and future developments.
We highlight the power of multimodal light manipulation and want to inspire new
eclectic approaches in this vibrant research community.
