The MySQL® database has become the world’s most popular open-source database because of its consistently fast performance, high reliability, and ease of use. It’s used in more than 8 million installations ranging from large corporations to specialized embedded applications on every continent in the world. (Yes, even Antarctica!)
PHP is a widely-used general-purpose scripting language that is especially suited for Web development and can be embedded into HTML. If you are new to PHP and want to get some idea of how it works, try the introductory tutorial. After that, check out the online manual.
Wikipedia is an encyclopedia written collaboratively by its readers. The site is a wiki, meaning that anyone, including you, can edit almost any article. Wikipedia contains a huge amount of information on all sorts of subjects ranging from politics, science, history, music, religion, pop culture, and sports to everything and anything in between.