I love segments! And for those of you wondering why I love them, or for those of you wondering what the heck segments are: I’ve written a post about segments in Google Analytics, that I invite you to read. In short: using segments makes your Google Analytics life a whole lot more interesting because it specifies your data, which allows you to get more insight into the behavior of your audience. And that’s what you want, an insight that you can turn into action.
Source : Yoast