A method, computer program product, and system includes a processor(s) initiating a web conferencing session between a host and a client, by the client receiving a presentation and transmitting the presentation to a semantic engine, wherein the semantic engine performs an automatic machine learning session to generate a presentation concepts list comprising concepts relevant to the presentation, and progressively displaying the presentation in a thin client application on the client. The processor(s) monitors on the client, during the web conferencing session, activities executed on the client and extracts web concepts related to the activities executed on the client. The processor(s) determines an interest level of a user of the client in the presentation, based on determining a presence or absence of a relationship of each web concept to one or more of the concepts relevant to the presentation and displays the interest level in a graphical user interface.