The term PHP is an acronym for PHP: Hypertext Preprocessor. PHP is a server-side scripting language designed specifically for web development. PHP can be easily embedded in HTML files and HTML codes can also be written in a PHP file. The thing that differentiates PHP from a client-side language like HTML is, PHP codes are executed on the server whereas HTML codes are directly rendered on the browser. That is why when you look at a website's source code you cannot see the PHP code that is on the page but you can see the HTML.
Early PHP was not intended to be a new programming language, and grew organically, with Lerdorf noting in retrospect: "I don't know how to stop it, there was never any intent to write a programming language [...] I have absolutely no idea how to write a programming language, I just kept adding the next logical step on the way." A development team began to form and, after months of work and beta testing, officially released PHP/FI 2 in November 1997.
You cannot run PHP that is inside of a .html file. It must be in a .php file.
PHP 8 was released on 26 November 2020. PHP 8 is a major version and has breaking changes from previous versions. New features and notable changes.
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