A stream is a way of thinking about digital information for which there may be no ending point. The most conventional form of digital information is the file. Files always have a beginning and an end, but streams may or may not, and therefore software which uses streams must not require finding the end of the file in order to process it. Streams are usually delivered in packets which are self-contained, and usually allow seeking (i.e. fast forward) for further points in the streams. They are particularly important when dealing with large sizes of digital information, so most video and audio on the Internet is streamed.

Players that read streaming media must first process a certain amount of the stream (at least one packet) in order to display anything. The buffer is a word for computer memory that stores digital information that will later be processed. The computer memory can either be in the form of RAM or a partial temporary file that the media player constructs from the stream. Buffers in streaming media players usually will store a certain number of seconds of information, to avoid jerky on-off playback; if the media player runs at a certain rate, and there is some latency (i.e. intermittent interruptions or slower downloading) in the stream, the display process will run more smoothly if there is a fair amount of information in the buffer before the playing begins. Of course, if the rate at which the stream comes in is too slow, there will inevitably be some interruptions in the playback, but if there is a lot stored in the buffer, the periods of play before interruptions will be long enough to be intelligible.

Audio Types:

.mp3 - The creation of MP3 compression (.mp3) created a revolution in audio formats that changed the music industry, as music files became easily accessible from the Internet. MP3 has proprietary encoders, but there are plenty of free encoders available, and there are no limits on MP3 playback.
.wmp - files are proprietary audio files from Microsoft.
.ra and .rm - are proprietary audio files from Real Networks.
Ogg Vorbis (.ogg) - is a compression format that offers higher-quality than .mp3.
acc Plus (.aac, .mp3) - is a variant similar to the .mp3 encoding scheme that offers much higher quality at smaller sizes than .mp3 files.

Here is a list of available players to play your specific audio file formats:

Real Player
Quicktime Player
Macromedia Flash Plugin
Winamp Media Player - Winamp is a fast, flexible, high-fidelity music/video player for Windows. Winamp supports playback of many audio (MP3, OGG, AAC, WAV, MOD, XM, S3M, IT, MIDI, etc) and video types (AVI, ASF, MPEG, NSV), custom appearances called skins (supporting both classic Winamp 1.x/2.x skins and Winamp 3 freeform skins), audio visualization and audio effect plug-ins (including two industry dominating visualization plug-ins), an advanced media library, Internet radio and TV support, CD ripping, and CD burning.
VLC Media Player - VLC (initially VideoLAN Client) is a highly portable multimedia player for various audio and video formats (MPEG-1, MPEG-2, MPEG-4, DivX, mp3, ogg, ...) as well as DVDs, VCDs, and various streaming protocols. It can also be used as a server to stream video.
Real Alternative Player - Real Alternative will allow you to play RealMedia files without having to install RealPlayer/RealOne Player. Supported: RealAudio (.ra .rpm), RealMedia (.rm .ram .rmvb .rpx .smi .smil), RealText (.rt), ReadPix (.rp), RealMedia embedded in webpages.
Media Player Classic - A great all-in-one player based on the Windows Media Player 6.4. Supports most formats if you have the codecs installed like DivX, XviD, AVI, MOV, MPEG1/2, RM. Built-in MPEG2/SVCD/DVD codec. SVCD/CVD switchable subtitle support.
QuickTime Alternative - QuickTime Alternative will allow you to play QuickTime files (.mov, .qt, .3gp and other extensions) without having to install the official QuickTime Player. It also supports QuickTime content that is embedded in webpages.
MPlayer - MPlayer is a movie player for Linux (and runs on many other Unix systems, and non-x86 CPUs, like Windows, Mac...). It plays most DVD, VCD, MPEG, VOB, AVI, OGG/OGM, VIVO, ASF/WMA/WMV, QT/MOV/MP4, FLI, RM, NuppelVideo, YUV4MPEG, FILM, RoQ, PVA files. Mencoder is a converter that supports many input video formats.

You can listen to internet radio through other systems than your computer speakers. For instance, if you have a laptop, there is generally a audio jack designated for headphones. Your stereo system generally has a line-in input, often labelled auxiliary input, which allows sound sources to be plugged in from the outside, like tape decks, portable CD players, MP3 players, etc. And there is generally a switch which toggles between auxiliary input, and input from your radio, CD player, DVD player, etc, which must be set. If you simply plug a stereo line from the headphone jack on your computer to your line-in input on your stereo system, you can listen in hi-fidelity. If you have Bluetooth Wireless, simply plug in the inputs as you would on any other item you are using Bluetooth for.

A codec is a downloadable software encoder or decoder for a particular media format that is geared towards a specific computer platform. Codecs function much like plugins for browsers, and are used by players or authoring software to work with the specific media type. Most codecs that you will come across are decoders that are geared to presenting media content to players. Most media players have a list of websites that supply codecs and will go in search of them when a file is played that requires a particular codec; otherwise use a search engine to look for it. Free-Codecs.com also lists free versions of codecs and is generally up to date.