WPF(Windows Presentation Foundation) is a graphical subsystem to display user interfaces. One should be wondering we have win forms for this then what is need for WPF. WPF has the following advantages over win forms.
Anywhere execution
We use XAML in wpf which makes it possible to use the same code for various types of applications like windows, web or silver light etc.
Binding
Binding objects is very easy in WPF. Without writing single code we can bind two objects.
Common Look and Feel
We can make use of styles and the same style is applied to our entire application as and when required.
Declarative Programming(XAML)
We describe abstractly what need to be done and visual studio will do the directive programming for us in the back end.
Express Blend and animation
WPF internally uses Directx, directx is used for animation, so WPF can do animation as well. Express Blend is a tool which is used to create animation and reuse it.
Fast Execution
WPF uses directx and supports software, partial, hardware rendering depending on requirement, whereas win forms uses software rendering only.
Graphic Independent
WPF uses DIP(device independent pixel) 1 dip =1/96 of an inch and it adjusts itself to any screen based on this .