All software is based on the principle of manipulating data. Whether it's the code that runs inside your VCR to start recording at a specific time, or air traffic control software, code is always working with data in one form or another. Today, we find that sophisticated applications store their data in a "database", a central repository of
data overseen by a Database Management System, or DBMS. A DBMS does two things. Firstly, it handles the storage of the data. Secondly, it provides mechanisms for retrieving data as well as adding, removing, and changing data. A DBMS endeavors to do this in the most efficient way possible.