In this paper we analyze the components of virtual worlds supporting learning proposals in these scenarios. The analysis takes into account significant changes in the conceptualization of virtual worlds that have led to overcome their status as distinct social technological environments, where practices take place isolated from the physical setting. The increased transparency of mediations, which traditionally have placed limits on the immersion and interaction between people and virtual objects, implies that they occupy a secondary place as a key element in the definitions of virtual worlds. Based on this consideration, the article analyzed the other components that support the social layer of virtual worlds and provides them with a high educational potential. Among other aspects of formation, the article explores the ability of technological mediation, immersion and social presence, non-physical materiality or practice that is itself part of a virtual world so defined. Finally, the need to design appropriate educational theories and hybrid scenarios that result from the interactions in-out of physical reality is discussed.