Container hosting is typically when you don't want to setup a complete server by yourself. Instead, you rent/borrow a server, and your 'container' runs on that server.
In order for a server to run containers, the server needs a container runtime installed such as containerd, CRI-O, Docker Engine etc.
It's common (but wrong) to think that "container" == Docker, but that's not the case- it's just very good marketing on Docker's part
Under the hood, all linux containers use a combination of `cgroups` and `namespaces` to create the illusion of isolation between your containers.
Upload your `Dockerfile` (or `Containerfile`) to a container hosting service and that service will build your container and run it for you so that you don't have to. Ta-da!