Borders are linked to a territory. They also are social, cultural and mental. Of all aspects, national, regional, ethnical, generational or else, they draw the outlines of identities. To raise a frontier, is to create or to reproduce the constitutional norms and values of these various belongings. Contesting the frontier is to question the definitions of "us" and "them", repainting the contours of what is included in these belongings and what is not. The ubiquity of frontiers in our lives and their impact on our relations is at the heart of the conferences cycle 2018-19.