PHP is a free open source programming language that is used to develop powerful web applications. 

It is very easy to learn, and gives you great power.  I use PHP and MySql for all my websites and it works out very well.

PHP is fast and is all executed server side which means no one will see your PHP code, all they see is the same HTML.

Main benefits of PHP is that it will work on any system that has a PHP interpreter unlike asp which is usually only works on Windows Servers.

PHP.ini settings

For production servers I suggest you set

display_errors = Off

Which will help prevent some information from being leaked due to coding errors.

For coding in PHP I prefer to use TextPad it gives me an easy to use environment with line numbers that come in handy for

 Instead for production servers you should log the information a file

log_errors = On

error_log = C:\yourfilenamehere.txt

Speeding Up your PHP Code

You can get a 40% to 100% PHP speed increase by using the Zend Optimizer.

The Zend Optimizer is free and runs on various platforms.

http://www.zend.com/store/products/zend-optimizer.php