A specific form of sample rate conversion. Downsampling refers to converting a higher sampling rate to a lower one. For example, converting audio recorded at 96 kHz down to 44.1 kHz for CD production. Downsampling often comes in to play with Internet audio and other formats where there are bandwidth limitations. In those contexts it sometimes also implies bit depth reduction (which is also a common way to reduce the file size of audio data), but that is by no means assumed, and is not technically part of downsampling.
