This paper is an introduction on the Causal Theory of Memory, one of the most discussed theories in philosophy of memory in the present days. We begin with Martin & Deutscher’s formulation of the theory, in which the authors present three criteria in order for a given mental state to be considered an instance of memory, amongst them, the famous causal criterion, which stipulates that a memory must be causally connected to the past experience. Subsequently, we discuss if these criteria are necessary and sufficient for memory and we present two theories that complement these criteria with an epistemic and a phenomenological criterion, i.e., the Causal Epistemic Theory and the Causal Autonoetic Theory. We then introduce the concept of memory traces, which are, according to Martin & Deutscher, the causal link between the memory and the past experience which created this memory; we present the model of traces as structural analogues and the model of distributed traces and discuss the problems which arise for each of these models of traces. Afterwards we focus on the concept of causality and present the Causal Procedural Theory, which offers a different conception of causality that does not focus on the memory traces, but on causal process itself. Lastly, we present the theory called Discontinuism, a theory about the relation between memory and imagination, which follows directly from the Causal Theory of Memory.