How is the undo tree used in Vim?

Question

This answer says:

Vim\'s undo/redo system is unbeatable. Type something, undo, type something else, and you can still get back the first thing you typed

Answer 1

The package undotree is written in pure vimscript so no requirement.

And add this to your vimrc before it is too late:

  set nobackup
  set noswapfile
  set nowritebackup
  set undolevels=10000         " use many levels of undo
  set history=10000    " After nocompatible

  if has('persistent_undo')
    set undodir=$HOME/.vim/undo
    set undofile 
  endif