NDI, from NewTek, moves broadcast-quality video over a normal network: any source announces itself, any receiver on the LAN can take the feed. A VJ laptop, an OBS stream rig, and a camera can share pictures with nothing but a switch between them.
Its rise tracked the streaming era, where routing many sources beat pristine cabling. Latency is low but real, roughly a frame or two, fine for IMAG and streams, worth counting in tight reactive chains.
In visuals work NDI is the interchange layer between machines, complementing Syphon and Spout, which do the same job between apps inside one machine.