Connect iPhone to a computer with a USB cable
Open Finder (macOS Catalina or later) or iTunes (Windows or macOS Mojave or earlier)
Select your iPhone in Finder or iTunes
Choose “Back Up Now” to start an immediate backup
If prompted, enter your device passcode and trust the computer
To encrypt the backup, check “Encrypt local backup” (if available) and set a password
Keep the iPhone connected until the backup finishes
Disconnect the iPhone only after the backup completes
To back up over Wi‑Fi, go to Settings on iPhone
Tap your name, then iCloud
Tap iCloud Backup
Turn on “Back Up This iPhone”
Ensure Wi‑Fi is connected and the iPhone is plugged in to let the backup run
Confirm backup status in Settings > your name > iCloud > iCloud Backup (look for the latest timestamp)