How does PHP Work?

[miragek]

We have all seen many question on StackOverflow that are founded upon the idea that PHP works like Javascript. Where the person clearly does not understand that PHP is a Preproccessor and only works before the page is sent out. A clear example of this is in the following code, where \[code\]runCommand()\[/code\] will not run when the user presses the button.\[code\]<a href="http://stackoverflow.com/questions/2034501/<?php runCommand(); ?>">Click Me!</a>\[/code\]as it would in Javascript\[code\]<a href="javascript:runCommand();">Click Me!</a>\[/code\]I've seen many questions like this that are from new people that just simply don't realize 'how' PHP works. My question is: Where is a great resource that explains how PHP works?. I want to be able to redirect people to a page that can get them going on the correct track and know what being a Preproccessor means.(This also allows me to be lazy and not have to write an explanation every time it comes up, but don't tell anyone!)If you don't know of a place that describes this well, feel free to provide your own interpretation.As Carl Smotricz points out, there is a part of PHP that can be used outside of the browser. But I'm mainly talking about in a Apache enviorment where a user requests a web page, and expects to get something back, usually in HTML.