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ABSTRACT: Classical geometry, based on standard topology, often admits pathological phenomena such as space-filling curves. To address such irregularities, model theorists have developed the framework of o-minimal structures, which supports a well-behaved notion of geometry. In this talk, I will introduce the fundamental properties and examples of o-minimal structures. Recently, model theorists are applying o-minimality to Dulac’s Problem, which asks whether a real analytic vector field on the sphere can admit infinitely many limit cycles. I will describe how model-theoretic methods contribute to this finiteness question, with a focus on the role of transition maps near singularities. The main analytic ingredients in this setting are almost regular germs and multisummable functions. In joint work with Speissegger, we have established the o-minimal structure in which such functions are definable. I will outline the definition of this structure and the methods that I used to show o-minimality.