The term "terrorist-generated online content" refers to the online dissemination of statements aimed at motivating other persons, directly or indirectly, to commit a terrorist crime, for example by glorifying the latter.
A comparable definition can be found in the EU - Regulation on combating terrorism, Directive (EU) 2017/541 of the European Parliament and of the Council of 15 March 2017 on combating terrorism.
Terrorists use the Internet for the dissemination of propaganda. Propaganda generally takes the form of multimedia communications providing ideological or practical instruction, explanations, justifications or promotion of terrorist activities, for example in virtual messages, presentations, magazines, audio and video files and video games.
For instance, online propaganda includes contents such as video footage of violent acts or video games developed by terrorist organizations that simulate acts of terrorism and encouraging role-play. Such content may be distributed using a broad range of tools, for example websites, virtual chat rooms and forums, online magazines, social media platforms, and popular video and file-sharing websites. Particularly social media platforms such as Twitter and Facebook, and popular video and file-sharing websites, such as YouTube are prominent tools for radical group to publish their propaganda containing violence, hate and fake information.
The promotion of violence is a common theme in terrorism-related propaganda and its distribution via the Internet exponentially increases the audience that may be affected. Furthermore, extremist groups disproportionately target youth (adolescence and young adults) to spread propaganda as they are more vulnerable to extremist ideas and dangerous behaviours. ➜ [Child protection on the Internet]
The fundamental threat posed by terrorist propaganda relates to the manner in which it is used and the intent with which it is disseminated. Propaganda aimed at potential or actual supporters may be focused on recruitment, radicalization and incitement to terrorism, through messages conveying pride, accomplishment and dedication to an extremist goal. For example:
Advocating or calling for acts of violence (e.g. "They should all be shot / burned / gassed.", "On the gallows with them!").
The glorification of terrorist attacks with the aim of persuading other actors to imitate them (e.g. "9/11 was a great revenge on the infidels. Further punitive actions should follow.")
Demonstration of the effective execution of terrorist attacks to those who might be ready to adopt such behaviour.
If you discover a page that contains false reports or content that is inhumane, you can report the page to the relevant operators (e.g. Facebook).
Childline will help anyone under 19 in the UK with any issue they’re going through. If you want to talk about anything, whether it’s something big or small, the trained counsellors of Childline will support you. Call them for free on 0800 1111 or see their homepage. Childline will help anyone under 19 in the UK with any issue they’re going through.
To report online material promoting terrorism and extremism please visit this website.
 United Nations Office on Drugs and Crime (2012). The use of the Internet for terrorist purposes. In collaboration with the United Nations Counter-Terrorism Implementation Task Force. Retrieved from: https://www.unodc.org/documents/frontpage/Use_of_Internet_for_Terrorist_Purposes.pdf
 Hassan, G., Brouillette-Alarie, S., Alava, S., Frau-Meigs, D., Lavoie, L., Fetiu, A., ... & Sieckelinck, S. (2018). Exposure to extremist online content could lead to violent radicalization: A systematic review of empirical evidence. International Journal of Developmental Science, 12, 71-88.
 Harpviken, A. N. (2019). Psychological vulnerabilities and extremism among wyestern outh: A literature review. Adolescent Research Review. doi:10.1007/s40894-019-00108-y