Prezi is a popular presentation tool. You create it completely online and can collaborate with colleagues anywhere. Prezi is best when you embed lots of images and films and the animation makes the presentation more of a journey than the standard linear presentation form. When you're finished you simply share the link so everyone can view the presentation! You can choose from many templates so you don't have to start completely from scratch and there are guides to help you build your presentation.
As with most tools the basic version is free but if you pay for a subscription you get many more functions and solutions.
Here is a short introduction to Prezi.
PowToon is a versatile and easy-to-use tool to create animated presentations that can then be easily uploaded to YouTube. There are lots of templates to get started with and there is a library of images and background music to choose between. You have certainly seen many PowToon videos already on YouTube.
Here's an introduction video created of course in PowToon!
Sway (by Microsoft) enables you to produce creative presentations but can also be used to create online course material, reports and storyboards. It offers lots of templates, guides as well as inbuilt search functions that will automatically suggest media you could use in your presentation or report. Sway is available if you have an account with Microsoft Office 365.
Here is a short introduction to Sway.
Emaze is another attractive tool for making and sharing animated online presentations. There are lots of great templates to start you off and you can then add your own photos, videos and text as you want. The free version offers plenty of scope but as always you get more features by paying a subscription to the advanced versions.
Here is a short introduction to emaze.