If you've got friends asking what MCAS is all about, this BBC article is a pretty good explanantion for non-technical people:
What went wrong inside Boeing's cockpit?
https://www.bbc.co.uk/news/resources...deadly_crashes
It's a bit out of date now - doesn't contain all the detailed discussion on software, trim wheels, other problems, that we've had in this thread, but it's a good starting point with pics and animations.