The digital space played a central role in the radicalisation processes of many perpetrators of past attacks: extremists including Anis Amri (Berlin, Germany), Brenton Tarrant (Christchurch, New Zealand) and Stephan Balliet (Halle, Germany) took advantage of social media platforms not only to gather and distribute information, and to network and stage, but also to exchange ideas with like‑minded people and sometimes even to share an attack live for thousands of viewers. It is through this communication by radical or extremist actors that we can learn much about the radicalisation processes that take place in the virtual world. The content and its presentation, as well as the way in which these actors communicate, are of central importance in that regard and can serve as a background against which to develop the most appropriate preventative and demobilising measures.
In the context of this research field, data retrieved from social media naturally has become increasingly important. This is exemplified by numerous scientific publications based on data from social media: for instance, Facebook, Twitter, YouTube and Instagram. An extremely large pool of data can now be accessed and used to develop and test hypotheses. These opportunities go hand in hand with limitations and pitfalls. This relates to potential ethical and data protection requirements, which certainly provide challenges for researchers but also many opportunities. While transparency and the guideline “maximising benefits and minimising harm” are essential throughout the entire research process, there are further principles and guidelines that need to be considered. In the first two sections, we summarise some key ethical considerations that a research process in this academic field should include and we provide insights into the main data protection principles to be observed. We then highlight the opportunities available to and balancing acts required of researchers in this regard. In the third section, we discuss the interplay between researchers, data sources and policies of platforms, and give some key recommendations.