This paper is intended as an introduction to the debate on net neutrality and as a progress report on the growing body of academic literature on this issue. Different non-net neutrality scenarios are discussed and structured along the two dimensions of network and pricing regime. With this approach, the consensus on the benefits of a deviation from the status quo as well as the concerns that are unique to certain non-net neutrality scenarios can be identified. Moreover, a framework for policy decisions is derived and it is discussed how the concept of neutrality extends to other parts of the Internet ecosystem.