attach is one of the most useful features of tmux. If you have no interest in tmux for pane and window management, you should use tmux for this. It can be a life saver if you ever get disconnected from the host machine or accidently close your terminal you can connect right back into the session you were just in using attach.
this command will simply attach back to tmux if you are ever disconnected
If you ever run long running tasks on a remote machine by sshing into this you should be doing it inside tmux, or something like tmux so that you do not loose your work.
attach to a specific session
If you have multiple sessions running you can select the session that you want
to attach to by passing
tmux attach -t scratch
for more information on how I navigate tmux, check out this full post
Also check out the full YouTube tmux-playlist to see all of the videos in this series.