A data store is the location where data resides permanently or temporarily. It responds to requests for storing and accessing data, but cannot initiate any actions. It represents data at rest, which can be computerized components, such as files or databases, or non-computerized components, such as names and addresses in an address book for example.
You design a data store using a resource object with a Data Store stereotype. Flows incoming to and outgoing from data stores must be created with the Resource Flow tool when using the DFD specific toolbox.