Kivy language file used by Kivy, an open source Python library used to develop multi-touch enabled, cross-platform applications; may contain rule definitions, a root widget, dynamic class definitions, and templates.

Widgets are the building blocks of GUIs in Kivy and a KV file can contain only one root widget. A Kivy rule applies to a specific widget and is used in a KV file to modify the widget, such as specifying interactive behavior or adding graphical representation of a widget. A Kivy dynamic class allows you to quickly create new widgets or rules without any Python declaration. Before being deprecated, Kivy templates were used to save the user time when styling content, like only having to specify the value of a button once for buttons that are used repeatedly. Templates were replaced by dynamic classes in version 1.7.0 of Kivy. Below is a simple example of a KV file containing a root widget. A KV file should always start with the Kivy header, with the correct Kivy language version used, and then followed by the content: #:kivy 1.5 Button:       text: 'Hi there'