In JavaFX, the Circle class is used to create a circle shape with a center point and a radius. A circle is a basic geometric shape that can be used to create a variety of visual effects, such as buttons, icons, or visual indicators.

Here's an example of how to create and use a Circle in a JavaFX application:

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.stage.Stage;

public class MyJavaFXApp extends Application {

    @Override
    public void start(Stage primaryStage) {
        // Create a new Circle object with a center point and radius
        Circle circle = new Circle(100, 100, 50);
        circle.setFill(Color.RED);
        circle.setStroke(Color.BLACK);
        
        // Add the circle to a Pane layout
        Pane layout = new Pane(circle);
        
        // Create a Scene object with the layout and set it on the stage
        Scene scene = new Scene(layout, 300, 200);
        primaryStage.setScene(scene);

        // Show the stage
        primaryStage.show();
    }

    public static void main(String[] args) {
        launch(args);
    }
}

In this example, we create a Circle with a center point at (100, 100) and a radius of 50. We set the fill color of the circle to red using the setFill() method, and set the stroke color to black using the setStroke() method. We then add the circle to a Pane layout, and set the Pane as the root of the Scene. Finally, we display the scene on the stage using the show() method.

The Circle class provides a number of methods for configuring the appearance and behavior of a circle. You can set the fill and stroke colors, add a shadow effect, and set the circle to be dashed or dotted. You can also use the setOnMousePressed() and setOnMouseReleased() methods to add event handlers that respond to user input.