Modern nations are generally divided  into a series of nested administrative units. While the actual nomenclature may vary - state or province or region, for example - the general principle is quite consistent. The nation overall is divided into  first order administrative units (ADM1). These are in turn divided into second order administrative units (ADM2), which are themselves subdivided into third order administrative units (ADM3), and so forth. There is no consistency as to how many levels a nation may have, but they most typically range from four to six.

Of course such a tradition of administering an area through a series of nested administrative divisions is not unique to the modern nation, and has a long history going back many centuries to the founding of polities extending over large geographical regions. What is distinctive about modern administrative units is that they typically are very precise in boundaries, involve more regular interrelationships with each other, and have more normative administrative processes in place than typical of most administrative units.