Tiit Tammaru is a Professor of Urban and Population Geography and Head of the Chair of Human Geography at the Department of Geography, University of Tartu. He is the member of the Estonian Academy of Sciences. He has also worked a guest researcher at the Geography departments at the Delft University of Technology, University of Utah, University of Helsinki and Umeå University. Tammaru leads the development of longitudinal linked censuses and registers data for urban and regional studies in Estonia. He is theorizing the paradigmatic shift in spatial inequality studies from residential neighborhood approach to activity space-based approach. Together with colleagues from Delft and Tartu he is developing the concept of vicious circle of segregation that focusses on how social and ethnic inequality and segregation are produced and reproduced across multiple life domains: homes, workplaces, schools, leisure time activity sites. He is also interested in how global challenges and poly-crisis may impact migration and segregation processes in physical space. He seeks answers to pertinent questions, such as: Do digital transitions and decreasing housing affordability in large cities create new opportunities for rural areas? An example of such studies is the paper titled „Did the pandemic bring new features to counter-urbanisation? Evidence from Estonia“ recently published in the „Journal of Rural Studies“. His other recent works include edited books and journal special issues such as „Urban Socio-Economic Segregation and Income Inequality: A Global Perspective“ (Springer), „Spatial underpinnings of social inequalities: A vicious circles of segregation approach“ (Social Inclusion) and „Segregation and mobility: Understanding the nexus between inequality, segregation and sustainable urban mobility“ (Journal of Transport Geography).