PHP is a hypertext preprocessor, meaning that its function is to produce something functional; in this case HTML, the markup language that web browsers understand. This allows dynamic information to be reached or calculated and then translated into something a browser understands in real time. Without this capability, websites would be very static, non-interactive, and incapable of providing unique experiences for each viewer. Imagine a world without web-based client logins, bill-pay, or online forums like Facebook and Twitter.
