Borders define and divide. They separate, contain, and protect—but they also reveal, contrast, and give form. A border is never neutral. It marks a threshold: between inside and outside, self and other, signal and noise. This issue invites films that explore borders across scales—biological membranes, political frontiers, cultural lines, perceptual limits. We are interested in works that examine how borders are drawn, enforced, resisted, dissolved, or reimagined. What happens at the edge? Where does one system end and another begin? Can a border be porous, unstable, or generative? From cells to nations, from identities to ecologies, from visible lines to invisible thresholds—this issue seeks films that engage the contradictions of borders: as sites of separation and connection, of violence and transformation, of definition and possibility.