Icecast Docs — Glossary

Source client: A source client is an external program which is responsible for sending content data to Icecast.
Some source clients that support Icecast 2 are Oddcast, Ices 2, Ices 0.3 and DarkIce.
Slave server (Relay): The slave server in a relay configuration is the server that is pulling the data from the master server. It acts as a listening client to the master server.
Master server (Relay): The master server in a relay configuration is the server that has the stream that is being relayed.
Mountpoint: A mountpoint is a resource on the Icecast server that represents a single broadcast stream. Mountpoints are named similar to files (/mystream.ogg, /mymp3stream).
When listeners connect to Icecast, they must specify the mountpoint in the request (i.e. http://192.168.1.10:8000/mystream.ogg). Additionally, source clients must specify a mountpoint when they connect as well. Statistics are kept track of by mountpoint. Mountpoints are a fundamental aspect of Icecast 2 and how it is organized.
Fallback mountpoint: A fallback mountpoint is configured with a parent mountpoint. In the event of the parent mountpoint losing connection with Icecast, Icecast will then move all clients currently connected to the now defunct mountpoint to it’s fallback mountpoint.

Icecast is free server software for streaming multimedia.