The subject of digital platforms and their treatment in competition law has attracted much attention, not only through investigations into Google, Facebook and Amazon, but also with the publication of several reports. The antitrust debate surrounding digital platforms is huge and encompasses polarised discussions on, for example, killer acquisitions, algorithm collusions, or the role of Big Data for market power. Some even refer to gaps when it comes to regulating platforms adequately. However, more practical, and somewhat overlooked, is the need for a solid definition of “multi-sided platforms”, allowing for their identification in the first place.