How should I back up my phone and computer?

Reviewed answer

Turn on the built-in automatic backup today. It turns a lost phone or ransomware into a hassle.

iPhone: search Settings for iCloud Backup and turn it on. Android: search Settings for Backup and turn on Google backup.
Mac: use Time Machine with an external drive. Windows: search Settings for "Windows Backup".
For photos and documents you can't replace, keep a second copy somewhere else, such as an external drive kept unplugged.
Once a year, try restoring one file or photo to make sure the backup really works.

Get help if

If files suddenly won't open, have strange names, and a note demands payment, unplug from the internet and don't connect your backup drive.