Online presentation

Show.Zoho

Creation and demonstration of presentations.
You are offered a set of very nice templates and ... Import PPT-files, tools for working with styles, widened library of cliparts. Joint activities and remote management of the demonstration of presentations.

There is a Russian version, but all explanations in English.

Google Presentations

Google Slides, part of Google Docs related to Google Drive and Google mail.
The benefits are free. You will have to pay only if you want to increase the already huge Google Drive. By the way, many give less disk space for a paid account.
So this option is very good.

The editor is convenient for those who are familiar with Microsoft Office (that is, practically all), it's just easier.
In addition, there is the possibility of working together.

Autosave, you just work, and the work done will not be lost when Internet breaks down, the computer crashes ...

Compatible with PowerPoint. The important thing, because PowerPoint is currently the standard. A huge base of presentations, templates. In addition, Internet is not everywhere, but it is necessary to show it. PowerPoint document is easier to show.

Prezi

A kind of Microsoft PowerPoint online.

Great, you do not depend on your computer, programs on it, everything is online, simple and fun.
You can use the proposed elements, media files and PDF.
100 Mb.
If you really like it, you can buy 500 Mb or even 2 Gb.