To put it simply, Icecast is a collection of programs and libraries for streaming audio over the Internet.

This collection includes:

icecast - a program that streams audio data to listeners.

libshout - a library for communicating with and sending data to an icecast server. It handles the socket connection, the timing of the data, and prevents bad data from getting to the icecast server.  It uses external programs, called "source clients", to originate the streams.

The source runs typically in the place where the audio is generated (e. g. a studio) and the Icecast server in a place where a lot of bandwidth is available (e. g., a colocation).

There are a number of source clients (encoders) currently available for use with icecast. Some are designed to work only with icecast1.  While others, such as OddCast, ices2, and darkice esigned to use icecast2.

An Icecast server is capable of handling content such as Vorbis over standard HTTP, Theora over HTTP, MP3 over the protocol used by SHOUTcast, AAC, and NSV over the SHOUTcast protocol (Theora, AAC, and NSV are only supported in version 2.2.0 and newer).  It has similar functionality to the proprietary media server program SHOUTcast, by Nullsoft.

For more informaion about IceCast, you can visit www.icecast.org.