In previous Windows-based platforms (such as Windows Forms and MFC), developers had to build their own animation systems from scratch. The most common technique was to use a timer in conjunction with some custom painting logic. WPF changes the game with a new property-based animation system. The following two sections describe the difference.
Imagine you need to make a piece of text spin in the About box of a Windows Forms application. Here's the traditional way you would structure your solution:
Create a timer that fires periodically (say, every 50 milliseconds).
When the timer fires, use an event handler to calculate some animation-related details, such as the new degree of rotation. Then, ...