Free Lossless Audio Codec (FLAC) is an audio codec that allows digital audio is compressed lossless so that the audio file size is reduced without any loss of information. Compressed digital audio FLAC algorithm typically can be reduced 50 to 60% of its original size, and decompressed in an identical copy of the original audio data. The downside is that the file takes up much more space than would be obtained by applying a lossy compression algorithm. FLAC is an open format with royalty-free license and a reference implementation which is free software. FLAC has support for tagging metadata, including album art, and quick search.
RealAudio is a proprietary audio format developed by RealNetworks and first released in April 1995. It uses a variety of audio codecs, ranging from low-bitrate formats that can be used over dialup modems, to high-fidelity formats for music. It can also be used as a streaming audio format, that is played at the same time as it is downloaded. In the past, many internet radio stations used RealAudio to stream their programming over the internet in real time. In recent years, however, the format has become less common and has given way to more popular audio formats. RealAudio was heavily used by the BBC websites until 2009, though it was discontinued due to its declining use. BBC World Service, the last of the BBC websites to use RealAudio, discontinued its usage in March 2011.