... When PHP parses a file, it simply passes the text of the file through until it encounters one of the special tags which tell it to start interpreting the text as PHP code. The parser then executes all the code it finds, up until it runs into a PHP closing tag, which tells the parser to just start passing the text through again. This is the mechanism which allows you to embed PHP code inside HTML: everything outside the PHP tags is left utterly alone, while everything inside is parsed as code. ...