Ultra thin magnetic films (UTMFs) consist of several layers of magnetic atoms deposited on a non-magnetic substrate. Advances in the fabrication and characterization of these materials allow researchers to fabricate films comprising multiple layers, each with a distinct and well-defined atomic structure. By carefully selecting the substrate, the atomic composition and number of layers it is possible to produce materials that exhibit a fascinating and diverse range of magnetic properties. The ability to finely tune the magnetic properties of these materials by varying the number and composition of the layers makes it possible to create UTMFs in which the magnetic moments are aligned perpendicular or parallel to the surface and which can exhibit a reorientation transition between these two orientations. In addition, a number of systems with a net magnetisation perpendicular to the plane have been shown experimentally to manifest a stripe phase consisting of elongated domains of alternating magnetisation direction. In this talk I will summarise some of the key properties of UTMFs and discuss how the stripe phase can be understood as the result of the competition between the ferromagnetic exchange and the antiferromagnetic dipolar interactions. I will present results from a recent series of simulation studies that, together with some analytical calculations, provide some insight into the nature of the stripe phase close to the reorientation transition.