In JavaFX, the GUI Applications were constructed using a Scene Graph. A scene graph is a data structure similar to tree, in modern graphical applications. It is the starting point of the application, and it is a collection of nodes
To display something in JavaFX You need to construct a scene graph using the nodes and set it to an object of the Stage class, the top level container of a JavaFX application.
A node is a visual/graphical primitive object of a JavaFX application.
Each node in the scene graph has a single parent, and the node which does not contain any parents is known as the root node.
In the same way, every node has one or more children, and the node without children is termed as leaf node; a node with children is termed as a branch node.
A node instance can be added to a scene graph only once. The nodes of a scene graph can have Effects, Opacity, Transforms, Event Handlers, Event Handlers, Application Specific States.
In a JavaFX application the javafx.scene.Scene class holds all the contents of a scene graph. While creating a scene it is mandatory to specify the root node.