Wow, Lua beat out both Javascript and Ruby to take the #10 spot in TIOBE's latest Programming Community Index. How is that possible given all the Internet companies, start-ups and web sites being coded up in Javascript and Ruby?

In a word, "mobile." Here's a quote from the TIOBE page:

"Creating software applications for mobile devices is hot. Think of the recent rise of Objective-C because of the iPhone and iPad we have seen. But now also scripting language Lua is getting more and more popular. The major advantages of Lua are its small footprint and fast performance. A year ago, Apple decided to allow Lua to run on iOS systems. Nowadays many popular iPhone apps have been written in Lua, including Angry Birds.

Traditional web scripting languages, on the other hand, have a hard time. They are quickly losing market share at the moment. Take a look at the decline of PHP, but also Ruby and Python are going down."

Let us add another one-word reason: "games." On the newest platforms from social networks to smart phones, games are the dominant category of application in terms of revenue, users and engagement. So long long live mobile, games and Lua. :-)