The earliest live audio offerings on the web were radio broadcasts streamed using RealAudio, introduced by Progressive Networks (now RealNetworks) in 1995. This new format--and technology--led to the rapid growth of streaming audio and video webcasts during the late 1990s. With the subsequent development of competing formats, RealAudio's market share has deteriorated, but it is still a popular choice for streaming radio broadcasts, and it is still the format of choice for streaming digital audio reserves in music libraries. One advantage of RealAudio is the support of SMIL files, which allow a series of audio files to be played consecutively without prompting from the user. This feature is particularly useful with longer works, such as operas and multi-movement works, which are typically divided into multiple tracks on compact disc recordings.
RealNetworks applications in support of RealAudio include a player (RealPlayer), encoder (RealProducer), and streaming server (RealServer). In July 2002, RealNetworks launched Helix, an open-source initiative that builds on programming code released by the company. The Helix Community currently offers a player (Helix Player), encoder (Helix Producer), and server (Helix Server), all of which are developed to support RealAudio.