for a home computer: some external hard drives come with auto back up features if you lose you data you can find the backup form before the problem and get you data back
A good plan for backing up data is to setup an automatic backup to an external drive or cloud based storage on a regular basis. This will ensure that no data is lost and can easily be recovered.
backing up data
using floppy diskettes
third party
maintenance
Backing up your iOS device basically putts all your data From your iOS device on your computer. This is great when you want to migrate data from 1 old iOS device to a new one.
so you dont lose it......... . . . .
modem
You can store a backup copy of site.
wipe the hard drive
Backing up.
It means it's backing up all of your songs , apps and photos while syncing.. That why if you delete anything you'll have all of your data on iTunes