As described in the feature structured data, the structure of a database
is described through metadata which is also stored in the database.
A software application does not need any knowledge about the physical data storage
like encoding, format, storage place, etc. It only communicates with the management
system of a database (DBMS) via a standardised interface with the help of a standardised
language like SQL. The access to the data and the metadata is entirely done by the
DBMS.
In this way all the applications can be totally seperated from the data. Therefore
database internal reorganisations or improvement of efficiency do not have any influence
on the application software.