How does PHP stack up to other languages?

Once again as I get ready to teach an Intro to PHP course, I always start by asking the question:  Why should you want to learn PHP?   It's been around for a while now, and in the fast-paced ever changing landscape of web development, is it still the best thing to learn?   There's certainly a few other choices out there, (such as Java, Python, Rails, and ASP.net) if you're seeking to learn to build dynamic web sites.   And if you're hoping to make a living as a professional web developer some day, it's a good idea to do a little research before you make the investment of time and effort (and money) in learning.

How popular is PHP?

PHP is powering some of the most trafficked and powerful sites on the web.  This includes Facebook (http://developers.facebook.com/opensource/), Craigslist, Yahoo, The Whitehouse (whitehouse.gov) and many others..

I found a few good (and fairly recent) articles on this subject:

http://verens.com/2008/02/19/popularity-of-php-vs-java/ (2008)

And also this one:

http://www.itexaminer.com/php-wins-geek-popularity-contest.aspx (2009)

And this:

http://www.odinjobs.com/blogs/careers/entry/perl_php_python_and_ruby (2007)

So I'm still feeling pretty good about living in the PHP world.  I also have a pretty decent handle on working with Python, having taught an introductory course on that subject a number of times.  It's a wonderfully elegant language. But I haven't yet tried python as a server-side scripting language, just because I haven't really needed to.   But it look like it is making strides.

I'm a bit surprised for all the buzz I hear about Rails that it's not making bigger gains.

Reasons many companies give for using PHP:

• Designed for Web scripting (as opposed to some other options which can be made into web scripting languages)
• High performance
• Large, Open Source Community
• Robust Documentation
• "Code-in-HTML" paradigm
• Integration, libraries, extensibility
• Tools: IDEs, debugger
• Low training costs, doesn't require a CS degree to use