PowerPoint files are called presentations. Whenever you start a new project in PowerPoint, you'll need to create a new presentation, which can either be blank or from a template. You'll also need to know how to open an existing presentation.
If you've opened the desired presentation recently, you can browse your Recent Presentations instead of searching for the file.
If you frequently work with the same presentation, you can pin it to Backstage view for easy access.
You can also pin folders to Backstage view for easy access. From Backstage view, click Open, locate the folder you want to pin, then click the pushpin icon.
A template is a predesigned presentation you can use to create a new slide show quickly. Templates often include custom formatting and designs, so they can save you a lot of time and effort when starting a new project.
It's important to note that not all templates are created by Microsoft. Many are created by third-party providers and even individual users, so some templates may work better than others.
Sometimes you may need to work with presentations that were created in earlier versions of PowerPoint, such as PowerPoint 2003 or PowerPoint 2000. When you open these types of presentations, they will appear in Compatibility mode.
Compatibility mode disables certain features, so you'll only be able to access commands found in the program that was used to create the presentation. For example, if you open a presentation created in PowerPoint 2003, you can only use tabs and commands found in PowerPoint 2003.
In the image below, you can see that the presentation is in Compatibility mode. This will disable some PowerPoint 2013 features, such as newer types of slide transitions.
To exit Compatibility mode, you'll need to convert the presentation to the current version type. However, if you're collaborating with others who only have access to an earlier version of PowerPoint, it's best to leave the presentation in Compatibility mode so the format will not change.
You can review this support page from Microsoft to learn more about which features are disabled in Compatibility mode.
If you want access to all PowerPoint 2013 features, you can convert the presentation to the 2013 file format.
Note that converting a file may cause some changes to the original layout of the presentation.