Links and versions
Every change is a version. The link never moves. This is the promise the rest of the product is arranged around.
A new version is a draft
When you update a site, the new version is saved and nothing changes. The link and every embed keep serving what they served a minute ago. It goes live when you publish it, and not before.
That is deliberate, and it is the difference between a link you can send to fifty people and one you cannot. A link that changes when somebody else decides it is finished is not something you would put in an email.
Old versions keep working
Every version that has been published has its own permanent address — /v/3/ under the same host — and publishing a new one does not take it away. The version that was live becomes archived, not deleted.
A draft has no such address. It is work you have not decided to publish, so it is not served on the site's own host at all — only you can see it, from the version rail, and anyone who guesses the number gets nothing.
Which means going back is a button, not a restore: put an older version live and the current one is archived in its place. Nothing is copied, nothing is lost, and the record of what happened stays honest.
Adding and removing files
A folder's Files tab, beside the site, has Add files and a remove button on each file. Drop files or a folder onto the tab to add them; a file with the same name as one already there replaces it. A removed file stays in earlier versions.
Each change is a new version, and it goes live straight away, unless the site needs approval: then it waits as a draft for an approver, like any other version.
A single page can have files added too, from Add files under Make changes. It becomes a folder, and the page stays what the link opens on. The other way, a folder down to one page is a single page again, and a folder down to one PDF opens on it. A folder that loses its index.html opens on a list of what is inside. The last file cannot be removed: delete the site instead.
To replace every file at once, open Upload a new version and upload the folder, a .zip or a PDF. That is saved as a draft, like a pasted update. The limits are a folder's: 25 MB a file, 50 MB and 500 files in all.
Renaming does not move anything
The title and the address are separate on purpose. Fix a typo in the name and the link is untouched. If you do change the address, the old one redirects permanently and is never given to anybody else — a link somebody bookmarked must not one day open a stranger's site.
How long we keep them
Free keeps the last five versions; older ones give their storage back, and their permalinks say so rather than 404ing silently. Pro and Team keep all of them. The live version is never dropped, whatever its age — the link has to keep working, and that outranks a plan limit.