Abstract: Sparse inhomogeneous random graphs are a natural generalization of the well-known Erdos Renyi random graph, where vertices are characterized by a type and edges are independent but distributed according to the type of the vertices that they are connecting. These graphs undergo a phase transition in terms of the emergence of a giant component exactly as the classical Erd ̋os Renyi model. In this talk we will introduce an alternative approach, via large deviations, to prove this phase transition. This allows a comparison with the gelation phase transition that characterizes coagulation processes and the phase transition of condensation type emerging in several systems of interacting components.