Integrated electronics reorganized the 20^th century. By learning to pattern and control the flow of electrons on a chip, the integrated circuit put billions—now trillions—of transistors onto a sliver of silicon and turned computation into something that could be produced using large-wafer-scale manufacturing. Integrated photonics promises a comparable shift, but along a different axis. Whereas electronic integrated circuits (EICs) process information by steering electrons and current, photonic integrated circuits move information by steering light. Photonics adds a degree of freedom that electronics cannot easily reach, and the two technologies are increasingly being developed together.