Prezi is an online presentation tool, that you can use to create interesting presentations that are non-linear and exciting because you can zoom in on some fine print or drill down into an image or diagram (check out the magnifying glass theme).
There is a free version and two premium versions, but you can do a lot with the free version, like try it out and see if you like it. There are also 2 EDU packages, the free edu package gives you 500 MG of storage and allows password protection, unlike the commercial free version. The premium package allows working offline for $59 per year for a teacher account, and gives you 2 GB of storage space.
There are themes you can use to easily get started creating a Prezi. The most important thing you should learn first is the transformation tool. Click on any element that you have added to the Prezi and the transformation tool will pop up and allow you to move, size, rotate or scale your element. Since a picture is worth a thousand words, here is an image of the transformation tool:
You can import PowerPoint presentations into Prezi, but not all of the PowerPoint conventions will work on Prezi. See prezi.com/support for more on that.
Here's a sample of one I really like, related to social media. The second one is one I created as a parent informational presentation (my first Prezi).
Social Media 101
My first Prezi
Now check out this video to see how to get started.
Video tutorial Getting Started with Prezi