In Qt Quick, all its components have built-in properties such as width, height, and color that are attached to the components by default. However, Qt Quick also allows you to create your own custom properties and attach them to the components you declared in your QML script. A custom property of an object type may be defined in an object declaration in a QML document by adding the property keyword before the type (int, float, and so on) keyword, for example:

property int myValue;

You can also bind the custom property to a value by using a colon (:) before the value, as shown in the following code:

property int myValue: 100;