RMVB are files that store multimedia audio and video materials, the content of which can be streamed using the network. It is a type of RealMedia format that is coded in a way that allows the use of a variable bit rate (VBR). The material is divided into time fragments (those more difficult to compress use more bandwidth). This allows to maintain a constant quality of the obtained starting material.

The RMVB format was developed by RealNetworks. It is optimized in terms of video content and therefore more efficient.