Apple or Android? For your contacts, Android is complicated. For Apple, it's pretty easy.
Unless you turn off That One Button.
iCloud, Apple's storage and backup system, keeps most of your information as a duplicate of your phone information. It's how you can move from one iPhone to another easily. Just sign in to access your old info and you're good to go.
But iCloud doesn't quite work like that with your contacts. Many people do not know that it keeps your contacts strictly in iCloud, not your phone. So, if you turn on That One Button - Poof! All your contacts are gone.
Business Insider writer Jim Edwards tells about his experience with this weird Apple setting.
It is the ultimate smartphone nightmare. I was innocently picking through my phone's "settings" section, trying to figure out how to free up enough space on my phone to accept Apple's latest operating system update when suddenly ... all the contact info for everyone I know just disappeared.
Everyone — gone.
I couldn't even call my mom (she just moved and got a new phone number).