Back up / Backup
Different formsBack up is the verb; backup is the noun or adjective.
Back up
Use when
You need the verb meaning make a copy for recovery or provide support.
Example
“Back up the database before applying the migration.”
Backup
Use when
You need the noun or adjective for a recovery copy, system or role.
Example
“Store the encrypted backup in a separate region.”
Quick check
backup the database, create a back up, back-up the files
Usage note