Although RFB started as a relatively simple protocol, it has been enhanced with additional features (such as file transfers) and more sophisticated compression and security techniques as it has developed.
RFB was originally developed at Olivetti Research Laboratory (ORL) as a remote display technology to be used by a simple thin client with Asynchronous Transfer Mode connectivity called a Videotile.
In order to keep the device as simple as possible, RFB was developed and used in preference to any of the existing remote display technologies.
VNC was released as open source software and the RFB specification published on the web.
[1] A community version of the RFB protocol specification which aims to document all existing extensions is hosted by the TigerVNC project.
H.264 has been researched for encoding RFB data, but the preliminary results (using Open H.264 format) were described as lackluster by a TurboVNC developer.
The VNC protocol expresses mouse button state in a single byte, as binary up/down.