The Windows Presentation Foundation (WPF) is a graphical display system for Windows. WPF is designed for .NET, influenced by modern display technologies such as HTML and Flash, and hardware-accelerated. It is also the most radical change to hit Windows user interfaces since Windows 95. It allows you to build advanced user interfaces (UIs) that incorporate documents, media, two-dimensional (2D) and three-dimensional (3D) graphics, animations, and weblike characteristics.
In a pre-WPF world, developing a Windows application would have required the use of several different technologies. For instance, in order to add forms and user controls to your application, you needed to use the Windows Forms included in the .NET Framework. You had to use GDI+ to create images and 2D graphics. To add 3D graphics, you would have needed to use Direct3D or OpenGL.
WPF is designed to be a unified solution for application development, providing a seamless integration of different technologies. With WPF, you can create vector graphics or complex animations and incorporate media into your applications to address all of the areas just listed.
The following links are useful to learn the WPF programing model:
1- WPF Official Website
2- Pete Brown’s Blog
3- Welcome to the Windows Presentation Foundation Resource Guide
From C# Learners
4- Windows Presentation Foundation (Introduction)
http://www.csharplearners.com/category/wpf/
From MSDN
5- Introduction to WPF
http://msdn.microsoft.com/en-us/library/aa970268.aspx
6- WPF Architecture
http://msdn.microsoft.com/en-us/library/ms750441.aspx
7- WPF Videos
http://windowsclient.net/learn/videos_wpf.aspx
8- WPF Samples
http://archive.msdn.microsoft.com/wpfsamples
http://archive.msdn.microsoft.com/wpfsamples#controls
http://archive.msdn.microsoft.com/wpfsamples#wpfwindowssamples
http://archive.msdn.microsoft.com/wpfsamples#layout
9- What is New in WPF Version 4.5 Developer Preview?
http://msdn.microsoft.com/en-us/library/bb613588(v=VS.110).aspx
From Code Project
10- WPF: A Beginner’s Guide by Sacha Barber (MVP)
http://www.codeproject.com/KB/WPF/BeginWPF1.aspx
http://www.codeproject.com/KB/WPF/BeginWPF2.aspx
http://www.codeproject.com/KB/WPF/BeginWPF3.aspx
http://www.codeproject.com/KB/WPF/BeginWPF4.aspx
http://www.codeproject.com/KB/WPF/BeginWPF5.aspx
http://www.codeproject.com/KB/WPF/BeginWPF6.aspx
11- WPF and MVVM
http://www.codeproject.com/KB/WPF/MVVMEpisode1.aspx
http://www.codeproject.com/KB/WPF/MVVMEpisode2.aspx
http://www.codeproject.com/KB/WPF/MVVMEpisode3.aspx
http://www.codeproject.com/KB/WPF/MVVMEpisode4.aspx
12- Composite WPF
http://www.codeproject.com/KB/WPF/IntroductionCompositeWPF.aspx
http://www.codeproject.com/KB/WPF/IntroductionCompositeWPF2.aspx
13- WPF Controls
http://www.codeproject.com/KB/WPF/WPFOutlookBar.aspx
http://www.codeproject.com/KB/tree/WPFBreadcrumbBar.aspx
http://www.codeproject.com/KB/WPF/WPFExplorerBar.aspx
http://www.codeproject.com/KB/WPF/OdysseyRibbonBar.aspx
From C# Corners
14- WPF (An Introduction)
http://www.c-sharpcorner.com/UploadFile/nipuntomar/7881/
15- WPF and User Interactivity
http://www.c-sharpcorner.com/UploadFile/yougerthen/970/
http://www.c-sharpcorner.com/UploadFile/yougerthen/974/
http://www.c-sharpcorner.com/UploadFile/yougerthen/991/
http://www.c-sharpcorner.com/UploadFile/yougerthen/992/
http://www.c-sharpcorner.com/UploadFile/yougerthen/976/
From CodePlex
16- Microsoft Prism and WPF
http://compositewpf.codeplex.com/
17- Extended WPF Toolkit
http://wpftoolkit.codeplex.com/
18- WebCam Library for WinForm and WPF
http://easywebcam.codeplex.com/
19- WCF Guidance for WPF Developers
http://wcfguidanceforwpf.codeplex.com/
20- WPF Themes
http://wpf.codeplex.com/wikipage?title=WPF%20Themes
21- WPF Model-View-ViewModel Toolkit
http://wpf.codeplex.com/wikipage?title=WPF%20Model-View-ViewModel%20Toolkit
22- WPF Discussions