A Glossary of Internet Radio Terms — Plain-English Definitions
Updated
Internet radio comes with its own vocabulary — terms borrowed from broadcast, audio engineering, and streaming technology that don't always explain themselves. This glossary covers the terms you're most likely to encounter, defined in plain English, with enough context to make them genuinely useful. For a broader introduction to the format, see What is internet radio? For a deeper look at audio quality specifically, the guide to bitrate and audio quality goes further.
The Terms
AAC (Advanced Audio Coding) A digital audio compression format, and the successor to MP3 in most modern applications. AAC produces better audio quality than MP3 at the same bitrate — meaning it sounds more detailed and faithful at any given file size or stream speed. It is the standard codec for many streaming services and is widely used in higher-quality internet radio streams. Sometimes written as AAC+ (a variant optimised for low-bitrate streaming).
Algorithm In music and radio contexts, an algorithm is a set of computational rules that automatically determines what to play next, based on listener data. Streaming services use algorithms to recommend music. Internet radio, by contrast, is typically programmed by humans — a key distinction for listeners who want discovery rather than confirmation of existing preferences. See The Case for Human Curation for a longer treatment of why this matters.
Bandwidth The amount of data your internet connection can carry per second. Higher-bitrate streams require more bandwidth; on a slow connection, a 320kbps stream may buffer while a 128kbps stream plays cleanly. Most modern broadband and mobile connections handle typical internet radio streams without difficulty.
Bitrate The rate at which audio data is transmitted, measured in kilobits per second (kbps). Higher bitrate generally means better audio quality, though the codec used also matters. Common internet radio bitrates:
- 64kbps — Listenable, but thin and compressed; suitable for speech or background listening
- 128kbps — The standard for most internet radio; acceptable quality on most speakers
- 192kbps — Noticably better; the step where the improvement becomes clear on good headphones
- 320kbps — High-definition audio for streaming; the practical ceiling for compressed audio
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Buffering The short pause that occurs when a streaming player loads audio data faster than it can play it, building a small reserve before playback. Most players buffer a few seconds of audio in advance. "Buffering" as a problem usually refers to a stream that pauses unexpectedly because the incoming data rate can't keep up with playback.
Codec Short for coder-decoder. A codec is the algorithm used to compress and decompress audio data. Common codecs in internet radio include MP3, AAC, AAC+, OGG Vorbis, and Opus. The codec affects how much the audio quality degrades at a given bitrate — modern codecs like AAC and Opus are significantly more efficient than older ones like MP3.
Community Radio A category of radio station typically run by and for a specific geographic or interest community, often with non-commercial, locally relevant programming. Community radio stations are frequently staffed by volunteers and focused on voices and perspectives underrepresented in commercial broadcasting. For a full account, see Community & College Radio, Explained.
Cross-fade The technique of fading one audio track out while simultaneously fading the next one in, creating an overlap at the transition. A well-timed cross-fade makes the join between tracks nearly invisible. A clumsy one creates an audible collision of two pieces of music. Cross-fading is one of the core tools in radio programme sequencing — see The Art of the Radio Segue for the broader picture.
DAB (Digital Audio Broadcasting) A digital radio standard used for over-the-air broadcast radio in many countries, particularly in the UK, Australia, and much of Europe. DAB receivers pick up digital signals rather than analogue FM or AM signals. DAB radio and internet radio are both digital, but they reach listeners through entirely different means: DAB via broadcast transmitter, internet radio via IP streaming.
DAW (Digital Audio Workstation) Software used to record, edit, mix, and produce audio. While this is primarily a music production term, radio presenters and producers use DAWs to prepare pre-recorded segments, jingles, and programme elements. Widely used professional DAWs include Pro Tools, Logic Pro, Adobe Audition, and Reaper.
Format The complete programming identity of a radio station — its music policy, presenter style, pace, and target audience. More than a genre: format describes how a station sounds and behaves, not just what music it plays. See What Is a Radio Format? for the full explanation.
HD Radio A proprietary digital broadcasting standard used primarily in the United States, allowing AM and FM stations to transmit a digital signal alongside their analogue signal. Not to be confused with "an ad-free player" in streaming contexts, which typically refers to high-bitrate streams (see: Bitrate). HD Radio receivers are required to receive the digital signal.
HLS (HTTP Live Streaming) A streaming protocol developed by Apple, now widely used for delivering audio and video over the internet. HLS breaks a stream into small chunks and sends them sequentially, which helps with reliability and adaptive bitrate switching (adjusting quality depending on your connection speed). You may see .m3u8 file extensions associated with HLS streams.
Icecast An open-source streaming server software widely used for internet radio broadcasting. Icecast allows a station to host and broadcast audio streams to many listeners simultaneously. It is the most common alternative to SHOUTcast in the independent internet radio world and supports multiple codecs including MP3, OGG Vorbis, and AAC.
IP Radio Another term for internet radio — radio delivered over the Internet Protocol (IP) rather than via radio waves. IP radio is geographically unconstrained: a station can be received anywhere in the world with an internet connection.
Latency The delay between when audio is encoded at the broadcasting end and when it reaches the listener. In internet radio, a few seconds of latency is normal and unnoticeable for music listening. In live radio contexts where real-time interaction matters (phone-ins, live sport commentary), latency can be more significant.
M3U / M3U8 A playlist file format used to point media players to a streaming source. An M3U file doesn't contain audio; it contains a URL (web address) that tells the player where to find the stream. If you've ever clicked a "listen" link on a radio website and had it open in a media player, an M3U or M3U8 file was likely involved.
Metadata Information transmitted alongside an audio stream that tells the player what is currently playing — track title, artist name, sometimes album and artwork. When a streaming player displays "Now Playing: [Artist] — [Track]", it's reading metadata from the stream. Not all stations broadcast metadata; those that do provide a much more informative listening experience.
MP3 (MPEG-1 Audio Layer III) The most widely recognised audio compression format, MP3 was the standard for digital audio from the late 1990s through the 2010s. It works by discarding audio information the ear is least likely to perceive, reducing file size. At higher bitrates (192kbps and above) the quality is decent; at lower bitrates it can sound thin and artefact-heavy. Largely superseded by AAC and Opus for new streaming applications.
OGG Vorbis An open-source audio codec often used in internet radio streaming as an alternative to MP3. OGG Vorbis typically provides better quality than MP3 at equivalent bitrates. Not universally supported by all players, though compatibility has improved significantly.
Opus A modern open-source audio codec designed for streaming. Opus performs well across a very wide range of bitrates — from low-bitrate voice to high-quality music — and is now the preferred codec in many internet applications. Increasingly common in internet radio streaming.
Podcast An on-demand audio programme distributed as individual episodes, downloaded or streamed at the listener's convenience. Not the same as radio — podcasts are not live, they are not continuous, and they do not play on a schedule. Podcasts and radio serve different needs and increasingly complement each other.
Segue The transition between two pieces of audio — particularly the point at which one song ends and the next begins. A well-crafted segue is a key element of professional radio programming. See The Art of the Radio Segue for the full craft breakdown.
SHOUTcast A streaming server platform developed by Nullsoft (later acquired by various parties) widely used in internet radio's formative years. SHOUTcast directories list thousands of internet radio stations, many of them community and independent. Technically comparable to Icecast; both are used to host and broadcast streams.
Stream URL The web address that directly links to an audio stream. Pasting a stream URL into a compatible media player (like VLC) will begin playback of that station. Internet radio discovery platforms like 72FM handle stream URLs in the background, so listeners typically don't need to manage them directly.
VBR (Variable Bitrate) An encoding method where the bitrate of an audio stream changes dynamically depending on the complexity of the audio at any given moment — higher for musical passages with lots of detail, lower for simple passages. Contrasted with CBR (Constant Bitrate), which maintains a fixed rate throughout. VBR can produce better quality at the same average file size but is slightly less predictable for streaming applications.
Web Radio A common synonym for internet radio. "Web radio", "online radio", and "internet radio" are used interchangeably in most contexts.
Frequently Asked Questions
What is the difference between internet radio and a podcast? Internet radio is a live or scheduled continuous broadcast — you tune in and hear whatever the station is playing at that moment. A podcast is on-demand: individual episodes that you download or stream at any time. Radio is live and linear; podcasts are on-demand and episodic.
What does bitrate actually affect? Bitrate affects the level of detail in audio — the richness of textures, the clarity of high frequencies, and the dynamic range between quiet and loud sounds. At low bitrates, audio sounds compressed and thin; high frequencies in particular suffer. At higher bitrates (192kbps and above), the difference between a compressed stream and a high-quality recording becomes progressively smaller.
What is the best audio format for internet radio? For streaming at quality levels typical of internet radio, AAC (or its variants AAC+ and HE-AAC) and Opus are currently the most efficient codecs. Both provide better quality than MP3 at equivalent bitrates. At very high bitrates (256kbps+), the differences between codecs narrow, and the audio quality approaches that of uncompressed audio for most listening conditions.
Do I need special software to listen to internet radio? No. Platforms like 72FM are browser-based — you simply go to the website and start listening, with no download or installation required. Some listeners prefer dedicated internet radio apps or media players, but these are optional.
What is the difference between DAB radio and internet radio? DAB radio uses a digital broadcast signal transmitted over the air, received by a DAB-compatible radio set. Internet radio is delivered over the internet, receivable on any device with a browser or streaming app. DAB is geographically local (limited to where the signal reaches); internet radio is global.
Summary
Radio streaming has its own vocabulary, but the concepts behind it are mostly practical: how audio is compressed, how streams reach listeners, how stations identify themselves and their programming. Knowing the terms makes it easier to understand what you're listening to and to make informed choices about audio quality and format. For most listeners, none of it needs to be visible — good internet radio is simply good listening.