With well over ten million installations, MySQL is probably the most popular database management system for web servers. Developed in the mid 1990s, it’s now a mature technology that powers many of today’s most-visited Internet destinations.
One reason for its success must be the fact that, like PHP, it’s free to use. But it’s also extremely powerful and exceptionally fast—it can run on even the most basic of hardware, and it hardly puts a dent in system resources.
MySQL is also highly scalable, which means that it can grow with your website. In fact, in a comparison of several databases by eWEEK, MySQL and Oracle tied for both best performance and for greatest scalability (http://mysql.com/why-mysql/benchmarks).