rm RealNetworks, an internet streaming Media Company, is credited as the developers and owners of the proprietary RealMedia multimedia container format. The filename extension .rm refers to this format which is used as an audio and video wrapper to distribute digital media content over the internet. The first version of this container was released in 1997 and has been popularized for its ability to unpack the digital stream while it is being downloaded over computer networks such as the internet. The format is platform agnostic and works equally well on Microsoft Windows as it does on Linux or Mac OS.
webm The WebM extension is an HTML5 standard for distributing and viewing videos over the web. WebM is primarily designed for use on the web using the HTML5 tags <video> </video>. Its design is based on the Matroska container, video compression in the WebM file format is often done with VP8-enabled technology. WebM is a high quality, open-source, standard video format which lets users play videos on the web. It is specifically catered for video playback on the web and in web browsers. A unique aspect about the WebM extension is that it adapts to various bandwidths, processing environments, and is used over a wide range of media playing devices. The audio compression technology used in the WebM file extension is known as the OGG Vorbis Compression.