Windows Communication Foundation (WCF) is a very powerful framework for building connected systems in the Windows platform. WCF has many building blocks which can be used out-of-the-box to build complex applications. It also has many extensibility hooks where we can customize the framework by configuring or replacing many of those building blocks. This course will look at the extensibility points in WCF, from its description to the runtime to the channel model; also covering the extensibility in the WCF serialization. Most of the extensibility points will be described and presented with code demonstrating how it can be used to solve a real-life scenario.