1 Introduction
• RQ1. What are the current topics and contributions from NLP to extremism research?
• RQ2. What NLP techniques are used on extremism research?
• RQ3. How have NLP techniques been applied in the field of extremism research?

2 Contextualizing the concept of extremist discourse
2.1 Extremism and radicalization: differences and similarities
2.2 Extremism and other related concepts
2.3 Definition and operationalization of extremist discourse

3 Methodology

4 General descriptive analysis of the articles

5 NLP techniques for extremism research
5.1 Text pre-processing
5.2 Feature Extraction

6 Applications of NLP in extremism research
6.1 Classification approaches
6.2 Descriptive approaches

7 NLP Dataset & Tools
7.1 Datasets and data sources
7.2 Tools

8 Discussion and Conclusion
8.1 Answer to research questions
• RQ1. What are the current topics and contributions from NLP to extremism research?
• RQ2. What NLP techniques are used on extremism research?
• RQ3. How have NLP techniques been applied in the field of extremism research?
• RQ4. What NLP software tools are commonly used on extremism research?
• RQ5. Which publicly available datasets or data sources have authors used to conduct NLP experiments on extremism research?
8.2 Future trends and challenges
8.3 Conclusion