Committing Changes
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[graphviz]
----
digraph {
  edge [style=bold, fontname=arial, fontsize=24]
  node [style=bold, shape=folder, fontname=arial, fontsize=24, height=1, width=2]
  wtree [shape=plaintext, label="<working tree>"]

  subgraph cluster_git {
    label = ".git"
    fontsize=24
    fontname=arial
    objects [color=red, fontcolor=red]
    index -> objects [label=" git commit ", color=red, fontcolor=red]
    {rank=same; index; objects}
  }

  index -> wtree [dir=back, label=" git add <file>"]
}
----

* `git commit` commits 'staged' changes only - the 'index'
* there could be non-staged changes still in the working tree