At tripartite synapses, astrocytes are in close contact with neurons and contribute to various functions, from synaptic transmission, maintenance of ion homeostasis, and glutamate uptake to metabolism. However, disentangling the precise contribution of astrocytes to those phenomena and the underlying biochemical mechanisms is remarkably challenging. This notably results from their highly ramified morphology, the nanoscopic size of the majority of astrocyte processes, and the poorly understood information encoded by their spatiotemporally diverse calcium signals. This book chapter presents selected computational models of the involvement of astrocytes in glutamatergic transmission. The goal of this chapter is to present representative models of astrocyte function in conjunction with the biological questions they can investigate.