• two-sided markets
• two-part tariffs
• monopoly
• joint production
• indirect network effects
• adoption externalities
• complementarities
• two-sided platforms

The aim of this work is to analyze the definitions of two-sided markets and offer a possible reinterpretation of this literature thanks to the concepts of joint production and externalities. We describe the common framework of two-sided markets so as to recognize the presence of two different definitions. In particular, the definition by Rochet and Tirole (2006) is studied and compared with the features of joint production; whereas the definition elaborated by Rysman (2009) and others is treated in a context of indirect network effects. After this theoretical comparison, two monopoly models are presented: the model by Rochet and Tirole (2003) and the model by Armstrong (2006). The first model is analyzed as a model with complementarities in the production and externalities; conversely, the latter model is presenting some similarities with the approach of complementarities in the consumption. Finally, we derive a two-part tariffs monopoly model comparing it with the contribute by Rochet and Tirole (2006).