In Explorations, the Segment overlap technique lets you see the overlap of up to three segments.
For example, you might want to see how many of your users engage with your content on both mobile and desktop, and then see how that segment of users overlaps with users who convert. If the overlap is significant, you could then use the Path exploration technique to see whether the path to key event tends to begin with mobile and end on desktop.
Or you might want to see the overlap between desktop or mobile users and users from a particular country or city to determine where you want to focus your ad buys.