The authors look at transformations affecting border spaces, by using the concept of the 'mobile border' to examine the growing dissociation between border functions and border locations. The book bears witness to the claim that de/rebordering and de/reterritorialization processes are not equivalent. It questions them through the analysis of 'borderities,' a concept built upon a close reading of the writings of Michel Foucault and derived from 'governmentality.' 'Borderity,' any technology of spatial or socio-spatial division, could be defined as the governmentality of territorial limits. Although initially defined as a technology of power,borderity may also appear as a differentiated social and political quality. The contributors examine the production of mobile borders (section 1: technologies), their incarnation (section 2: biopolitics) and their complex interpretation (section 3: 'dispositifs'). By looking at how political subjects can be disabled and enabled, the proposed 'borderities' approach illuminates the question of how borders can be the site of both power and counter-power.