A template defines the data source type (Inventory, for example) and allows you to apply filters from a limited set.
A template is used across multiple feeds, so if you're planning on re-using a set of filters, it might make sense to create a template!
Templates consist of:
A name (for using in the "Feeds" menu)
A data set (Inventory, Web, CRM, or multiple!)
Filters (optional)
To create a template:
Navigate to "Templates" page
Click "Add Template"
Name your template
Select your data set
Add filters!
Once you click "Apply Saved Filters", you can hit "Add Template" and you will be able to reuse this to create feeds!