"The Terrorism Knowledge Base is sponsored by the National Memorial Institute for the Prevention of Terrorism (MIPT), a non-profit organization dedicated to preventing terrorism or mitigating its effects", in collaboration with The National Counterterrorism Center (NCTC) which is "the primary center for US government analysis of terrorism".
Operated by the U.S. Government, this is what they want you to think about terrorism and its prevention. Picture that; when you want to know some important facts and details, they tell you that its a matter of national security and they withhold the information. This is the most secretive administration in U.S. history. So when they offer information, ...
It is not only their determinedly (and hypocritically) self-oriented viewpoint, in light of the strict secrecy which this government maintains regarding any useful facts, this operation can most easily be understood as more of their propaganda.
That said, and understood, it's sure to be a source of interesting, if not complete, information for somebody. Time and testing will tell.
Paid for by the beleaguered U.S. taxpayers.