PHP is an interpreted programming language which is designed to support web-based interactive applications.
Instead of lots of commands to output HTML (as seen in C or Perl), PHP pages contain HTML with embedded code that does "something" (in this case, output "Hi, I'm a PHP script!"). The PHP code is enclosed in special start and end processing instructions <?php and ?> that allow you to jump into and out of "PHP mode."
The best things in using PHP are that it is extremely simple for a newcomer, but offers many advanced features for a professional programmer. Don't be afraid reading the long list of PHP's features. You can jump in, in a short time, and start writing simple scripts in a few hours.
Although PHP's development is focused on server-side scripting, you can do much more with it..
I use the image below from David Sklar's excellent book, Learning PHP (ISBN: 978-1-491-93357-2). Please note This image is not released under Creative Commons and the Publisher, or its licensors, retain copyright for this image. I am exceedingly grateful to the publisher for their permission to use this image on my page (it's really good).
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