I don't understand "casual dating" or "FWB" can someone explain it to me

Like the title says. I just don't understand these concepts. They seem so foreign to me. I've never had a casual thing and I've never had a FWB before. I'm a very average looking guy so I mean it's not like these things are easy to find for me anyway but regardless it seems strange. I've had girlfriends and yes I have had one night stands before but they were all horrible and I did not like them. They left me feeling so hollow and thinking "wtf did I just do that for?"

Like, how do you have sex with someone who you have no emotional attachment too? It seems kind of... pointless to me. I'm a man who loves sex just like most people out there but I love sex with someone I can continually have sex with, someone i care about, someone who cares about me. Who I know is not having sex with other people. It kind of just ruins the whole thing for me if I know that this person is going to leave and go fuck someone else tomorrow.

I also need to have some sort of other connection with this person other than looks. Like you could be the most attractive person on the face of the planet but if your personality doesn't match its such a turn off and there is no longer any physical attraction.

Also, how does it work? Do you hang out with this person? Do you cuddle? Do you have deep conversations when you're laying there naked after having sex? Or is it they come over you fuck and they leave? How do you find people like this too? It seems for some people that's all they find is someone else who wants casual and for other people they can never find a person like that even if that's what they are looking for?

Anyway, I literally have no problem with people who do these things. If that's what you want/need then do what makes you happy. We are all humans and we all have needs. I just want to know more about it because I actually do wish I was capable of having a FWB. I wish I was more capable of having casual flings but everytime I talk with a new person that's what my focus is on. It's not on the other 4 women in a "roster." (If I had one, I don't lol)

Any comments or discussion is welcome. I'm just curious is all to see other people's perspective on this subject.