This work in the format of interview opens the Special Issue of Vol. 2, 2022 dedicated entirely to the theme of borders starting from different multidisciplinary perspectives. The interviewed guest is Thomas Nail, Professor of Philosophy at University of Denver, and author of a now classic book Theory of Border (Oxford University Press, 2017). For many years, he has been studying the social, economic and political dynamics that are activated along border devices. During the interview, the Editors of the Journal – Prof Filippo Pergola and Prof. Raffaele De Luca Picione - discuss with the guest about a series of topics related to the definition of borders, their dynamics of movement, processes of in-betweenness, and both the spec-ificities and diversity of border types (the fence, the wall, the cell, and the checkpoint). The study of borders is shown to be an essential means for understanding human phenomena in the contemporary world.