What are dependency properties in WPF

What are dependency properties?
These dependency properties belong to one class but can be used in another.

Consider the below code snippet:-
<Rectangle Height="72" Width="131" Canvas.Left="74" Canvas.Top="77" />

Height and Width are regular properties of the Rectangle. But Canvas. Top and Canvas.Left is dependency property as it belongs the canvas class. It is used by the Rectangle to specify
its position within Canvas.