Exploring the dark side of the web: Collection and analysis of US extremist online forums

Contents in extremist online forums are invaluable data sources for extremism research. In this study. we propose a systematic Web mining approach to collecting and monitoring extremist forums. Our proposed approach identifies extremist forums from various resources, addresses practical issues faced by researchers and experts in the extremist forum collection process. Such collection provides a foundation for quantitative forum analysis. Using the proposed approach. we created a collection of 110 U.S. domestic extremist forums containing more than 6,40.000 documents. The collection building results demonstrate the effectiveness and feasibility of our approach. Furthermore, the extremist forum collection we created could serve as an invaluable data source to enable a better understanding of the extremism movements.