The habit that prevents disasters.
WHEN TO BACK UP
Before running any generated code or command Before any database change Before editing site files Before bulk changes to data Before applying a formula across a spreadsheet
WHY
Generated instructions that look correct may do something else.
A backup turns a disaster into an inconvenience.
WHAT A BACKUP MUST BE
Downloaded, or stored somewhere other than the thing being changed.
A backup on the same account is lost in the same event.
FOR WEBSITES
A full account backup before any significant change.
FOR DATABASES
An export before any query that writes.
FOR SPREADSHEETS
A copy of the file, not just undo.
FOR FILES
A copy of the original before editing.
TESTING THE BACKUP
Occasionally, confirm you can actually restore from it.
An untested backup is a hope.
THE RULE
If you cannot undo it, back up first.