PHP4 is the latest incarnation of PHP – the "PHP Hypertext Preprocessor". It's a programming language for building dynamic, interactive web sites, originally devised by Rasmus Lerdorf way back in 1994. Since then it's been through a great many changes, and has been adopted by web programmers all around the world. So what exactly is it? In technical terms, PHP4 is a cross-platform, HTML-embedded, server-side web scripting language. Let's take a moment to define these term