What other languages do you use in addition to PHP?

I write a fair amount of Java, C and assembler code.

Why did you decide to use PHP for Drupal, instead of other options such as Java?

More than one language will get the job done, so yes, I think there are good alternatives to PHP. Like any programming language, PHP has its advantages and its weaknesses. I don't regret my choice of PHP though.

The Web is built by millions of individuals, many of whom are amateurs. They continuously update, tweak and rebuild their Web sites. Scripting languages like PHP lend themselves to that, and are widely available at affordable prices. It would have been very difficult to get critical mass if Drupal was written in a programming language like Java. Not because Java isn't as good a language, but simply because Java isn't as accessible as PHP.

Drupal started almost accidentally (through experimenting with a message board in college), and got its name via a typo. What other significant unexpected events have led to Drupal being where it is today?

Probably the most important unexpected event was the Howard Dean campaign in 2004. Part of the campaign was the "Deanspace" site, which used Drupal as its underlying platform.

After the elections Deanspace grew into a Drupal-based grassroots organising platform called CivicSpace. Even though CivicSpace is a spinoff distribution based on Drupal 4.2, many innovations from CivicSpace have been incorporated back into the Drupal project itself. Is this correct, and what are some of these features?

That is correct. They contributed many different improvements. The most important feature that came out of the DeanSpace effort was probably Drupal's installer and the notion of install profiles. More importantly, I would say, is that Deanspace helped us bootstrap a successful ecosystem around Drupal. It helped us move from a "toy project" to a project that you could actually build commercial Web sites with.

I have heard you talk about the slashdot effect, and how Drupal can make sites slashdot-resistant. Can you explain this a little more?

For a long time, Drupal core has shipped with throttle functionality. It provides a congestion control throttling mechanism for automatically detecting a surge in incoming traffic. If the site gets linked to by a popular Web site, like Slashdot, your Web server might become overwhelmed. The throttle mechanism is utilised to temporarily disable CPU-intensive functionality. For example, in the site theme, you might choose to disable pictures when the site is too busy (reducing bandwidth), or in modules, you might choose to disable some complicated logic (reducing CPU utilisation). The throttle mechanism is activated automatically -- no manual intervention is required other than the initial configuration.