Introduction to the QML language
QML is a declarative language designed to describe the user interface of a program: both what it looks like, and how it behaves. In QML, a user interface is specified as a tree of objects with properties.
This introduction is meant for those with little or no programming experience. JavaScript is used as a scripting language in QML, so you may want to learn a bit more about it (JavaScript: The Definitive Guide) before diving deeper into QML. It's also helpful to have a basic understanding of other web technologies like HTML and CSS, but it's not required.