OLE DB providers can be created to access such simple data stores as a text file and spreadsheet, through to such complex databases as Oracle, Microsoft SQL Server, Sybase ASE, and many others. It can also provide access to hierarchical data stores such as email systems.
However, because different data store technologies can have different capabilities, every OLE DB provider cannot implement every possible interface available in the OLE DB standard. The capabilities that are available are implemented through the use of COM objects; an OLE DB provider will map the data store technologies functionality to a particular COM interface. Microsoft describes the availability of an interface as "provider-specific," as it may not be applicable depending on the data store technology involved. Note also that providers may augment the capabilities of a data store; these capabilities are known as services in Microsoft parlance.