What are the different types of contracts in WCF and how are they implemented?

In Windows Communication Foundation (WCF), contracts define the terms of communication between the service and the client. There are three main types of contracts in WCF:

1. Service Contracts: Service contracts define the operations that a service can perform. They are implemented using interfaces annotated with the [ServiceContract] attribute.
2. Data Contracts: Data contracts define the data types that are passed between the service and the client. They are implemented as classes annotated with the [DataContract] attribute.
3. Message Contracts: Message contracts allow for more control over the format of the messages exchanged between the service and the client. They are implemented using classes annotated with the [MessageContract] attribute.

Each type of contract plays a crucial role in defining the structure and behavior of a WCF service, ensuring seamless communication between different components. By implementing these contracts effectively, developers can create robust and efficient WCF services that meet the specific requirements of their applications.