Anons, I highly recommend a recent YT vid by Praying Medic, called "FISA is the foundation."
https:// www.youtube.com/watch?v=xqTZ6d59a7Y
It's pretty long, but you only need to watch the first half or so, which beautifully complements the docs that Q has linked to here. Praying Medic explains in simple, introductory terms how FISA works, and the way that (((they))) figured out how to abuse it.
As usual, PM explains a complicated concept very clearly. I find his vids helpful in redpilling normies, not only because I urge them to watch his vids, but also because they help me to understand how best to explain this shit myself.