What is iCloud on the iPhone?

I've got an iphone 5 and would like to know.

It's just lots of massive servers apple have where you can save your stuff. I wouldn't advice using it

It's a free service from Apple that lets you keep things like photos, calendars, songs and phone backups stored on Apple's servers, and then you can sync them across all of your Apple devices (iPhones, iPad, iPod, PC, Mac, etc.).It's got "cloud" in the name because "cloud" isn't just a fluffy white thing in the sky, it's also a technical term that means storing data on the Internet.

There are other similar services that aren't 100% Apple, for instance Dropbox lets you store and sync photos and files, and Google syncs those things too.