Databases are applications that are able to rapidly store and retrieve data. A relational database is a reference to how storage and organization takes place within a particular type of database. The term relational database is actually a shortened version of Relational Database Management System (RDBMS).

All data is stored in structured tables and have more or less the same appearance as other databases. However, the relationship between the tables is the thing that sets a relational database apart from the others. Popular commercial examples of RDBMS are Oracle, IBM DB 2, MS SQL, Ingres and of course the FOSS MySQL and SQLite.

In an RDBMS, all data that is stored in tables are normalized. Normalization is the process of removing repetitive data and placing it in a separate table with a reference number. The reference number is used in place of the original data thus reducing the usage of space. When that data is required, it is simply retrieved from the table where it is stored by using the reference number.

Data storage can be on a single file on a local machine (e.g. MS Access) or on a database server. If a database server is used, users will need to have the IP address of the server, Port number, User Name & Password and the name of the database to access the data.

SQL is a popular and powerful language that will allow you to play with and gain experience on RDBMS. Skills in this language are almost a staple requirement in any database oriented job these days.