Persisting annotations applied to an electronic hosted whiteboard

A plurality of annotations can be received for a presentation presented in a web conference. A respective relevance parameter can be assigned to each of the annotations. Each relevance parameter can indicate a relevance of a respective annotation to a portion of the presentation to which the annotation pertains. For each of the annotations, a decay model based on the respective relevance parameter can be generated. The decay model can indicate different durations of time the annotation is to be visible to different participants participating in the web conference based on respective expertise levels of the participants. Each respective annotation can be presented with the presentation in accordance with the decay model generated for the respective annotation.