Real Player is a commercial streaming audio/video solution. A competitor to WindowsMedia et al. There is a RealPlayer for Linux; alternatively you can get MPlayer and it can link to the RealPlayer libraries and play Real clips with that. They usually have the extension .rm or .ram.
RealPlayer forced MatthiasDallmeier to reinstall Windows after it highjacked all the default settings.
His fault for using Windows in the first place. ;) Wait - you can use Windows? --AristotlePagaltzis
RealPlayer forced zcat(1) to waste an entire afternoon learning how gnome uses mime-types to associate files with their applications. RealPlayer hijacked all Gnome's mime-types for mp3, wav, au, and a bunch of other formats, introduced new types for RealFlash? and flash2-preview (breaking Macromedia's flash plugin for Mozilla) and set itself as the default player for a bunch of flash games that it was completely incapable of playing. Don't think that you're safe from Real's crap just because you don't run Windows!
A word of warning - The people that make RealPlayer (and it's latest incarnation RealOne?) have a long history with SpyWare. Any which one version of RealPlayer may send of all sorts of information to Real.com, and might install other SpyWare without notifying you. (Comet-cursor, Gator, Bonzi-buddy, etc etc) - use with caution! --MarcelVanDeSteeg