Link makes tempo a shared network resource: every enabled app on the LAN converges on one beat grid, anyone can adjust it, and joiners lock in mid-bar. Ableton released it in 2016 and licensed it widely; DAWs, phones, VJ tools like Resolume, and countless patches speak it.
For visuals, Link answers where the beat is without audio analysis: phase-locked LFOs, clip retriggers on the bar, strobes that never drift. It carries no transport or content, only tempo, beat phase, and optional start-stop.
The practical split: Link for pulse-locked motion, audio analysis (Photism’s route) for reacting to what is actually sounding, timecode for prebuilt shows. Rigs commonly run two of the three.