In this paper we extend the usual notion of model (asa structure) to the more general notion of CauchySequence of Structures in a similar way as rationalsare extending to real numbers by means of Cauchysequences of rationals. We show that the structurespace Stτ is dense in thecomplete space CStτ of Cauchysequences of structures and that CStτ is compact in the (topo)logicalsense.