Interactive display synchronisation

A method and system to synchronise interactive content such as audio, video, images, text or graphics between two or more digital content renderers for the purpose of collaboration or video conferencing. A Presenter 30 changes or adds content at a first digital content renderer, the presenters interactive canvas 40. The Presenter 30 transmits to the Viewer 20 a first communication over a first communication channel which includes communication layer 50. The communication indicates a change in content rendered on the Presenters interactive canvas 40. The Viewer 20 transmits a request for the changed content over a second communication channel which includes application layer 60. This request may be sent to a Content database 110 or to the Presenter 30. The requested content is transmitted over the second communication channel to the second digital content renderer, i.e. the Viewers interactive canvas 40, to be rendered. The content renderer may be a WebRTC compliant browser.