PHP is a server-side scripting language designed for web development. It was originally created by Rasmus Lerdorf in 1994. PHP code is embedded into HTML code and interpreted by the web server before the page is sent to the browser. The presentation covers an overview of PHP including its history and syntax, control structures, CSS layout, selectors, and string manipulation functions. It also discusses file handling in PHP such as creating, deleting, copying, renaming files and checking file properties.