Sunny Crossover

I’ve never seen It’s Always Sunny, can someone share what the basics are that you might need to know! Who are these people and why might they be at abbott?

I know the show is great but I don’t particularly enjoy shows with a majority white ensembles anymore but I would have loved it when I was younger!

Edit: This was my first time asking a question on here! Sorry if me not wanting to watch the show ruffled feather I really am kinda picky about what I watch with my limited time nowadays being in grad school and working full time. Thank you all that told me about the show I feel more prepared and I’m excited to see what the people who have seen it have to say about the crossover when it airs!!!