About PHP 2 - PHP output 3 - Headers and variables 4 - PHP forms 5 - Debugging PHP 6 - Tainted input data 7 - Reading / writing files 8 - Common PHP functions MySQL and PHP Parsing XML with PHP System functions available within PHP include creating, opening, reading from, writing to and closing files on the server, executing system commands, create directories and modify file permissions in pre-determined directories. PHP can receive and process data from forms, save data to files, send by email and output a response to the browser. Some installations of PHP can use databases and generate tables and content in real time and some can also create images on-the-fly. Other uses of PHP4 include Java and Java Servlets support, XML parsing, Acrobat PDF file creation, GZip manipulation, DNS and socket use etc. PHP is cross platform and available for all types of web servers and has a lower memory requirement than other server-side languages.