The Sailfish SDK includes Sailfish Silica, a QML module for developing your own Sailfish applications.
Sailfish applications are written with a combination of QML and C++ code. QML is a declarative language provided by the Qt framework that makes it easy to create stylish, custom user interfaces with smooth transitions and animations. QML-based user interfaces can be connected to a C++ based application back-end that implements more complex application functionality or accesses third-party C++ libraries.
While the Qt framework includes the QtQuick module, which contains essential types for creating QML-based user interfaces, the Sailfish Silica module provides additional types specifically designed for use by Sailfish applications. When writing Sailfish applications with QML, you will need to make use of both the Sailfish Silica and QtQuick modules.
The Sailfish Silica module makes it possible to write user interfaces that:
have a Sailfish look and feel, so that they fit in with the visual style of standard Sailfish applications
behave consistently with standard Sailfish applications (for example, lists should gradually fade as they are scrolled past their limits)
make use of unique Sailfish application features, such as pulley menus and application covers