On Linux (and probably Unix) there are multiple consoles to work with. Within one session you can switch between a console and therefor work from different positions into the kernel. So in one console you can be a user and in the other root.
A colleague told me the history. In the past there where administrators working with their keyboard and a monitor. The monitor (console) was attached to a big server. Al the other administrators the same. So one server had multiple administrators.
With the transition to for example remote control as we known it today, they kept it.
So at one server, you have multiple consoles. That can be one administrator at the same time together with his colleagues.
To switch to another console, the TTY, you can use [ctrl] F2, F3 and so on. Or in a virtual you can use Key change.