Integrated loudness is the long-term LUFS number most delivery checks use.
Definition
Loudness over the whole program
Integrated loudness measures perceived loudness across the full selected piece of audio. For a song, that usually means from the start of the master to the end of the fade.
Because it averages over time, a short loud chorus and a quiet intro both contribute to the final number.
Contrast
How it differs from momentary and short-term
Momentary loudness reacts very quickly. Short-term loudness smooths over a few seconds. Integrated loudness keeps accumulating across the whole measurement window.
That makes integrated LUFS useful for delivery targets, but less useful for spotting a single harsh hit or an over-limited chorus.
Practice
Measure the same range every time
Start and stop the measurement consistently. Including silence, count-ins, or extra tail can change the integrated number without changing the actual mix balance.
Meter Core shows integrated, short-term, and momentary loudness together so you can see both the delivery number and the musical movement behind it.