PHP is a widely-used open source general-purpose scripting language that is especially suited for web development and can be embedded into HTML

Instead of lots of commands to output HTML (as seen in C or Perl), PHP pages contain HTML with embedded code that does „something” (in this case, output „Hi, I’m a PHP script!”). The PHP code is enclosed in special start and end processing instructions <?php and ?> that allow you to jump into and out of „PHP mode.”