A local edit history of a file is maintained when you create or modify a
file. Each time you edit and save the file, a copy is saved so that you can replace the current
file with a previous edit or even restore a deleted file. You can also
compare the contents of all the local edits. Each edit in the local
history is uniquely represented by the date and time the file was
saved.
Only files have local history; projects and folders do not.