PHP [5] (recursive acronym for PHP: Hypertext
Preprocessor) 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”. The PHP code is enclosed in special start and
end processing instructions that allow you to
jump into and out of "PHP mode.