This thesis analyses borders as sites of struggle in everyday life. Drawing on critical approaches across disciplines including international relations, security studies, citizenship, border, and migration studies, it argues for a perspective on borders as embodied encounters in everyday life as both a method and ethos of critical analysis. Drawing on empirical research in the contexts of the UK and Calais, this thesis presents an account of borders as everyday practices of segregation. In highlighting the everydayness of borders it points to the ordinary and often messy ways in which borders are made real in people's lives and also come undone. Framing the border in terms of segregation it traces how ongoing global histories of discrimination, domination, and racism underlying contemporary nation-state border-making are reproduced in everyday contexts and ordinary encounters in which we all become complicit. At the same time, this thesis elaborates a post-Wittgensteinian 'grammatical reading' (Pin-Fat, 2010; 2013; 2016) in order to trace how key debates within prominent critical approaches to borders, migration, sovereignty, and (bio)politics continue to be framed by the metaphysical seduction of nation-states and their borders as ontologically 'hard'. In doing so, it argues that several critical approaches risk reproducing the very borders they are often committed to challenging and risk undermining the possibility of solidarity and struggle. Instead, in turning to everyday life, this thesis proposes to read the ethical politics of borders and migration as ontologically 'soft': that is, contingent, socially constructed, and ordinary. Whilst this in no way makes borders less powerfully real or violent such a perspective, this thesis argues, provides critical insight into the politics of borders as sites and practices of struggle as well as into the ordinary ethics of 'migrant solidarity'.