Basic functionality
When you create blank collection, by default items are in their most basic form. They only have one field which is their name and functionality limited to the bare minimum.
You can use this state for quick lists of things or errands that will be short lived and likely forgotten in near future.
Extending items
To make items more usable, add and configure plugins.
Plugins add both, additional fields (including custom ones) and customizable behavior.
You can configure items to represent tasks, cars, your products or anything else.