How Family Trees Work
I have never been able to remember what a "first cousin" is, much less a "first cousin, once removed." But don't worry, there's YouTube. In the video below, C. G. P. Grey explains your family tree using simple diagrams. If you've ever scratched your head over what specific title your cousin Bob holds, here's how to sort it out:
There's a transcript along with a handy chart on Grey's website.
Don't forget the "footnote" video, Parallel and Cross Cousins Explained. For the record, I did not even know this was a thing:
See also, this epic Reddit thread on the video. And yes, when Grey said "prefix" he should have said "suffix." He knows.