Many people in the general public don't realize that you can have an iPhone and not have a computer, as long as you enable iCloud so you can migrate all of your apps and other information from one iPhone to another.

If you're doing an upgrade from one iPhone to another, you only have to turn on your iCloud for a time before the upgrade, then once you migrate, you can turn it off again.

Though, if you have no computer backup you should really keep iCloud on all the time so that if your phone gets eaten by a tiger, all your stuff can appear on your new phone.

I remember Mr. Jobs talking about this once.

Not the tiger part. That was just me.