Peak meter
A level meter that shows a signal's highest peaks rather than how loud it sounds.
Where a VU meter is deliberately sluggish, a peak meter reacts almost instantly and then falls back slowly so the eye has time to catch the peak. Broadcasting's PPM (peak programme meter), in its BBC and DIN flavours, integrates over a few milliseconds. Digital meters in a DAW show every sample in dBFS, and a red light at 0 means it has already clipped.
Two caveats. Sample peaks are not signal peaks: between two samples the reconstructed waveform can go higher, which is what true peak metering catches. And peak level says almost nothing about perceived loudness — the gap between it and RMS or LUFS is the crest factor.