- PHP is an open source scripting language used for web development that was created in 1995 and has evolved through several versions. It combines elements of Perl, C, and Java and allows embedding code in HTML. - The document outlines the history and evolution of PHP, its core features like script tags, data types, functions, and portability between Linux and Windows. It also provides tips on debugging, tools, and resources for learning more about PHP and the upcoming PHP 5 release.