OLE DB (Object Linking and Embedding, Database, sometimes written as OLEDB or OLE-DB) is an API designed by Microsoft that allows accessing data from a variety of sources in a uniform manner.
OLE DB separates the data store from the application that needs access to it through a set of abstractions that include the datasource, session, command, and rowsets.
On Oct 6, 2017 Microsoft announced that OLE DB was undeprecated, and a new version to maintain dependencies would be released in early 2018.
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.
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.