The paper develops a conceptual framework for interpreting the process of border changes in Poland since 1945. In this article, the author presents directions of change, and the functions, characterising Poland’s borders. A synthesis of relevant literature on borders shows how the specific functions of borderlands can be categorised into at least four overarching types, including by reference to barriers, peripherality and isolation, line of differentiation, and axis of integration. This then gains verification through empirical analysis of processes actually taking place along the borders of Poland. It proves possible to identify and take account of periods of isolation, transformation and European integration. However, the analysis also takes account of the most recent phenomena characterising the last few years (2020–2024), during which the Polish borders have moved back in a “rebordering” direction. The Author proposes the new concept of dynamic (cyclical) change of border function types after using Polish borders as an example of empirical analysis.