Often abbreviated “ADC,” automatic delay compensation is a feature/function found in many DAWs that automatically corrects for latency introduced by plug-ins. The function works by looking at the amount of delay added by each plug-in, then delaying the tracks without plug-ins until everything is phase-aligned. If different plug-ins are instantiated, with differing latency amounts, everything will be delayed to match the track afflicted with the longest total latency.
Needless to say, on a large session with many different plug-ins scattered and combined across many tracks, the calculations and DSP required for proper automatic delay compensation can be substantial.