THEMATIC SECTION: DIGITAL DATA, SECURITY AND MIGRATION EDITORIAL This special set of articles in Teorija in Praksa is dedicated to the theme of Digital Data, Security and Migration. The digital connectivity phenomenon is increasingly transforming the ways humans interact and deal with problems of collective action. Such a paradigmatic change is expanding the frontiers of research in terms of theories, methods and analysis. This thematic issue features articles covering two themes related to big data and security: digital activism, security, and migration. While digital data have been present in many other research areas, we believe the two themes highlighted in this issue offer both a breadth of coverage with respect to disciplines and examine topics with significant and current social, political and economic impacts. Digital activism is defined as the practice of using digital technology for social, political, economic or ecological change to promote different ideologies, social mobilisation, the promotion of democracy and tolerance, or exclusivity and hate. Although it has developed around the world in the past two decades, it is still impossible to identify the system of rules and instructions pursued by digital activists when seeking to achieve their goals. 386 However, we can recognise the different types of digital activism as well as the various strategies and tactics activists use. Given their speed, reliability, scale and low cost, digital networks have largely enabled the scope and reach of modern activism. Thus, digital activism encompasses all social and political campaigns that rely on digital network infrastructure. Two articles in this thematic block address the use of digital data and political activism. The first, by Car and Musladin, addresses the effect of digital data leaks on the threat to human security. In particular, they address whether and in which ways leaks of special personal data compromised the security of those affected in Croatia. The second paper by Mendez, Cosby and Mohanty concerns the topic of digital activism and analyses online discussion of healthcare in the United States by using tweets and considers the degree of polarisation in political activism on social media surrounding Obamacare. Both articles point to the importance of digital data use in public/social media and their potential social and political impacts. Another important topic is the use of digital data in migration and security processes. Collecting and analysing data is not new in the area of security and foreign policy but has been a regular practice of intelligence communities around the world for many years. The collection of large amounts of data around the planet and the spread of its use by intelligence communities and governments are backed by new technologies that are collecting unprecedented huge amounts of data. This has considerably shaped foreign policy particularly on migration, from international travel monitoring to TEORIJA IN PRAKSA let. 55, 2/2018 Dagmar RADIN, Leslie HossFELD refugee management and asylum seekers. While big data promoters enjoy the insights and the freshly acquired knowledge behind these enormous databases, others question the reliability of the data itself, as well as the bias of the inherent algorithms used to study threats, including those that refer to immigrant populations. The importance of this issue is shown by the recent wave of migrants from war and economically destroyed areas of the world to Europe and elsewhere. Two articles in this issue fall within this theme: Stanisic Kos et al. address the use of Twitter in the communications surrounding the 2014 Central American refugee crisis, while the paper by Lusa et al. discusses the effect of data on student attitudes to the migration crisis occurring along the Balkan Route. The use of digital data is set to grow in the near future and it is likely more studies will soon emerge that assess its social and economic impacts. We believe this special thematic block of articles makes for a useful introduction to what is likely to be an ever-present topic in the study of the social sciences. Dagmar Radin and Leslie Hossfeld* Guest editors 387 * Dagmar Radin, PhD, Associate Professor, Faculty of Political science, University of Zagreb, Croatia; Leslie Hossfeld, PhD, Professor and Head of the Department of sociology, Mississippi state University, United states of America. TEORIJA IN PRAKSA let. 55, 2/2018