What are some alternatives?
Microsoft Office Powerpoint - Create dynamic presentations with Microsoft PowerPoint, part of Microsoft Office Suite.
LibreOffice - Impress - Impress is a truly outstanding tool for creating effective multimedia presentations.
Ludus - Limitless creativity for your slides.
Google Drive - Slides - Create a new presentation and edit it with others at the same time — from your computer, phone or tablet. Free with a Google account.
Slidium - Rich Markdown Presentations editor for Mac
Keynote - Keynote for Mac, iOS, and iCloud lets you make dazzling presentations. Anyone can collaborate — even on a PC. And it’s compatible with Apple Pencil.