What is Stoicism? What did the stoics actually say?

I am not a stoicism expert. Though I find it interesting. A lot of people, especially on social media platforms, love to appeal to stoicism. I was lucky enough to study ancient history as part of my undergraduate degree, so my spidey sense gets tingling whenever people make simplistic claims about ancient authors.

Regarding stoicism, a youtuber/ streamer has recently done a very good job of critiquing a lot of BS stoicism that seems to be all over the place. Brooks at the Quarantine Collective has produced a series of videos and I wanted to have a place where they are all together. There are 5 videos in the series. If you think Brooks has a shitty take on stoicism, please let me know why in the comments below.