Online platforms play an increasingly important role in the European business landscape. Guided by questions from the European Commission's consultation on this topic, the paper aims to provide insight into the characteristics of online platforms and the resulting regulatory challenges. Issues such as the transparency of platforms or the organization of the Sharing Economy are currently under debate. Generally speaking, one main concern is that online platforms do not account for their users' interests sufficiently, resulting in hardly desirable market outcomes. The paper provides economic reasoning as to why this concern is not always justified and suggests possible policy measures in cases where regulatory action is necessary. The most important aspect being currently discussed in this context is the access to and the use of data. Data are at the center of most online platforms' business models. While regulation to ensure data protection is naturally important, this aspect is the main reason to refrain from overbearing regulation and to emphasize a rule-of-reason approach. European policy-makers need to find the balance between consumer protection and fostering new innovative business models.