This discussion paper explores the nature of online connectivity and, in particular, seeks to better understand how online connections are made in the very first instance of contact. There has been plenty of research on how to develop online connections once they have been made, but the question of how the initial contact is made has not received much attention. What is it that enables a potentially beneficial connection to be made with a previously unknown online communicator? We propose that the answer lies in online resonance, which we have called ‘e-resonance’. In this paper we consider what the characteristics, affordances and affecting factors of e-resonance might be. What sparks it off? This might not be the content of the post, but rather a secondary topic such as a mutually shared interest. What are the key indicators of e-resonance? Are there any specific skills associated with e-resonance? In response to these questions we discuss the possibility of ‘beyond verbal’ communication and the importance of being able to filter and select information on personal and conceptual levels. We also consider what e-resonance might mean for the author and reader of online messages in terms of stimulating new thinking. E-resonance is a riddle which is relevant to connectivity and knowledge creation in the online environment. However, we conclude that the riddle of online resonance remains, as yet, unsolved.