Data access typically refers to software and activities related to storing, retrieving, or acting on data housed in a database or other repository.
Historically, different methods and languages were required for every repository, including each different database, file system, etc., and many of these repositories stored their content in different and incompatible formats.
In more recent days, standardized languages, methods, and formats, have been created to serve as interfaces between the often proprietary, and always idiosyncratic, specific languages and methods. Such standards include SQL, ODBC, JDBC, ADO.NET, XML, XQuery, XPath, and Web Services.
Some of these standards enable translation of data from unstructured (such as HTML or free-text files) to structured (such as XML or SQL).