What are the benefits of using Storyboards instead of xib files in iOS programming?

What are the main differences between using Storyboards and xib files.

Specifically, what are the advantages or disadvantages of using a Storyboard?

Unfortunately, despite doing quite a bit of research, all I've been able to find on Storyboards are simple tutorials that show you how to set up a Storyboard, instead of concrete information explaining what they are.