At this time in HUD you're expected to type in the terms you're searching for. In the future, though Ubuntu anticipates that you'll use your voice.

Credit: Canonical

You'll also use HUD for system wide activities. In this example, since Ubuntu includes instant messaging as part of the desktop, I'm changing my IM status.

Credit: Canonical

You can use HUD to set the system condition. Here I'm getting ready to lock the screen, but you can also use it to turn the system off.

Credit: Canonical

Let's say you want to invoke a program from HUD, you can do that too. Here, I'm getting ready to invoke my e-mail program to send a message.

Credit: Canonical

Last, but not least, you can also HUD to select files—in this case an album—from within a program. The idea, as I'm sure you figured out by now, is to use the same interface for both the desktop at large and all its applications. Eventually, Ubuntu plans to use the exact same HUD interface for tablets and smartphones as well.

Credit: Canonical