Imagine you don't want to spend any money on server hosting.. but you still want Minecraft server hosting.
So how you can get one free? You can for example use services like Aternos, Ploudos or Minehut, and if you have a pretty decent computer, you can host it on your own and have some fun.
Let's talk about the case where you host a very beautiful Minecraft server on a PC, but when you are enjoying it at most, you have to leave and well, turn off the PC. What if your friend wants to play? Here's the idea of shared party hosting, applicable at every scale.
You are User 1 and you host the server, then when you need to leave, you turn it off and then automatically the application shares the minecraft server with everyone that has the permission to do so, so that User 2 for example, can start up your server again!
I know that it is unnecessarily complicated, but who cares, let's get some free hosting boys.