Much like PowerPoint, Prezi is a presentation tool. Unlike PowerPoint, Prezi allows you to show spatial relationships between elements in your presentation fairly easily and elegantly.
Prezi is online software as a service, so you’ll need to create an account and be able to work online to use it. They have a basic level that is free to everyone, but with a .edu email address, you can get get their enjoy account (the second of three levels) for free.
Their website has a learn section that can help you get going, and it includes tutorials, guides, manuals, templates, and more. (As you get started, you might also look at how people are talking about it here and here and here. And here. And of course, here.)