Trying a redesign used to mean duplicating a site: a second site with its own identity, its own hosting, and no way back. Forks replace that.
A branch of your content
A fork branches the site's database instead of copying the site. The site keeps its uuid, its hosting and its public address — only the content moves onto a branch. That makes the work promotable, and reversible.
Promote when it is ready
Promoting commits the fork's content onto the official branch as a new commit. Nothing is force-pushed and nothing is rewritten, so a second computer that syncs afterwards agrees with the first instead of merging your old pages back in.
And undo if it was not
Reverting a promotion restores the previous content, also as a commit going forward. Revert twice and you have redone it.
Redesigning a live site is now something you can do on a Tuesday afternoon.
