The data package is responsible for loading and saving all data in a Sencha Touch app. Most of the actions involving the data package are related to models, stores, and proxies:
Model: A model represents an entity your app cares about. User, Contact, Address, and Product could all be models. At its simplest, a model is just a collection of fields and their data, but they can do a lot more.
Store: A store is a collection of model instances. Mostly it is just a glorified array, but it also provides capabilities like sorting, filtering, and grouping, and it is capable of firing useful events.
Proxy: A proxy is responsible for the actual loading and saving of data into a store. Usually you will create an AJAX proxy which fetches data from your server and uses it to populate a store.
Data is only a part of the Sencha Touch ecosystem. To understand more about the framework and how it works, we recommend reading the following guides: