In the context of ITWissen.info, a limiter, in contrast to a compressor, is that the limiter does not affect the level below a certain level threshold, but compresses the level above it in a fixed level ratio.
The limiter avoids overloads and distortions of signals. It operates from the level threshold with a fixed level ratio of, for example, 10:1. If the threshold value is +20 dBu, for example, and the input voltage rises by 5 dB to +25 dBu (Decibel Unloaded), then the limiter reduces the level rise to +20.5 dBu. It thus remains approximately constant.
Audio limiters are electronic circuits that compress level peaks above full scale so that no overshoot occurs. The behavior of audio limiters is characterized by their compression factor and response time. If these are sufficiently short, audio limiters are not perceptible in the sound reproduction; if they have longer response and recovery times, this can result in the so-called pump effect.