An exterior space is a topological space provided with a quasifilter of open subsets (closed by finite intersections). In this work, we analyze some relations between the notion of an exterior space and the notion of a discrete semi-flow.On the one hand, for an exterior space, one can consider limits, bar-limits and different sets of end points (Steenrod,Čech, Brown-Grossman). On the other hand, for a discrete semi-flow, one can analyze fixed points, periodic points, omega-limits, et cetera.In this paper, we introduce a notion of exterior discrete semi-flow, which is a mix of exterior space and discrete semi-flow. We see that a discrete semi-flow can be provided with the structure of an exterior discrete semi-flow by taking as structure of exterior space the family of right-absorbing open subsets, which can be used to study the relation between limits and periodic points and connections between bar-limits and omega-limits. The different notions of end points are used to decompose the region of attraction of an exterior discrete semi-flow as a disjoint union of basins of end points. We also analyze the exterior discrete semi-flow structure induced by the family of open neighborhoods of a given sub-semi-flow.2010 Mathematics Subject Classification. 54H20, 37B99, 18B99, 18A40. Key words and phrases. Discrete semi-flow, periodic point, omega limit, positively Lagrange stable, region of attraction, exterior space, limit space, end point, end space, exterior discrete semi-flow, basin of an end point.Partially supported by the University of La Rioja PROFAI13/15 and an FPI grant from the Government of La Rioja.