A database is a file that is organized for storing data. Most databases are organized like a
dictionary in the sense that they map from keys to values. The biggest difference is that the
database is on disk , so it persists after the program ends. Because
a database is stored on permanent storage, it can store far more data than a dictionary, which is
limited to the size of the memory in the computer.Like a dictionary, database software is designed to keep the inserting and accessing of data
very fast, even for large amounts of data. Database software maintains its performance by
building indexes as data is added to the database to allow the computer to jump quickly to a
particular entry.
There are many different database systems which are used for a wide variety of purposes
including: Oracle, MySQL, Microsoft SQL Server, PostgreSQL, and SQLite
