What's the deal with Mandalorians?

Truth be told, I'm not the biggest Star Wars nerd on my home world. I've seen all of the films and played the Star Wars: X-Wing miniatures game. That's it. So, I don't know much of deeper lore, like what the hell a Mandalorian is. The origins of Beskar? Forget about it.

I ended up watching a bunch of YouTube videos in search of answers. Most of them only left me confused and with more questions than answers. Once again, the Templin Institute offered up my favorite summary.

[Image: Screen capture from the video]