MySQL, the most popular Open Source SQL database management system, is developed, distributed, and supported by Oracle Corporation. This is called relational database because all the data is stored into different tables and relations are established using primary keys or other keys known as Foreign Keys. All data in a MySQL database are stored in tables. A table is a collection of related data, and it consists of columns and rows. MySQL is released under an open-source license. So you have nothing to pay to use it. MySQL works on many operating systems and with many languages including PHP, PERL, JAVA, etc.