Data Stores
Lists of key/value pairs for your options and templates.
Data Stores are useful for defining field options you want to use in multiple places. They can also be used directly in templates when you need to loop through the same list repeatedly.
All Geppetto sites start with three data stores used to drive background settings. "Background Color", "Background Type" and "Overlay". Only edit these if you are actually changing the background partial. Feel free to take a look though. They're good examples of using a Data Store to drive a select menu.
Managing
You manage data stores in "Settings → Data Stores". Updating a data store will update all of the select menus or templates that use it.
Using in Select Fields
A Select field's options can come from "Custom Options" or a data store. Renaming a Data Store will not break its connection to the select field.
Template Usage
There are a couple of special helpers so you can use Data Stores in templates.
<!-- Loop through all of the items -->
{{#each (dataStore "social-links")}}
<a href="{{value}}">{{key}}</a>
{{/each}}
<!-- Print a human readable key from a value -->
{{dataStoreLabel "categories" post.category}}