Prior to the current wave of interest in mobile applications, the technology du jour was web applications. A lot of attention was paid to AJAX, Ruby on Rails, and other techniques and technologies that made the experience of using web applications close to, and sometimes even superior to, the experience of using a desktop application.
The explosion of web applications eventually drove the next round of enhancements to web standards, collectively called HTML5. Android 2.0 was the first version to add support for these HTML5 enhancements. Notably, Android supports offline applications and Web storage, meaning that HTML5 becomes a relevant technique for creating Android applications, without dealing with Java.