Switch between sessions in tmux?

I'm relatively new to tmux and use it just for local development. In some tmux tutorials, a person will list out their tmux sessions in an enumerated list. There is yellow highlight typically. Does anyone know what I'm talking about and how to do it? Secondly, would you say this is best practice? I'm over here with 8 iTerm2 tabs open :(

Here's a screenshot of what I'm looking for:

enter image description here

How do I exit a tmux session?

You can exit any window by typing 'exit' in the prompt.

How do I open multiple tmux sessions?

You can—and often will—have multiple tmux sessions on a single system, so you want to be able to see what they are. You can also show sessions using the shortcut ctrl–b–s.

What is Ctrl B in tmux?

ctrl-b, <arrow key> switch to the pane in whichever direction you press. ctrl-b, d. detach from tmux, leaving everything running in the background.

CTRL-b s

found it! Alex's answer is awesome as well. Note CTRL-b is my prefix, your prefix could be something else.