What is Windows Communication Foundation (WCF) and Windows Workflow (WF or Workflow)?

Windows Workflow Foundation (WF or Workflow) is Microsoft's technology platform for building workflow-enabled applications. The platform includes a set of tools for designing and managing workflows, a programming model for implementing workflow logic, a rules engine, and a workflow runtime execution engine. Workflow technology can be employed in a wide range of application scenarios.¹    Windows Communication Foundation (WCF) and Windows Workflow (WF) services provide the building blocks for creating Service Oriented Architecture (SOA) applications, and are the focus of AppFabric . WCF provides a unified programming model for developing SOA applications that communicate across the web, including interoperability with applications built by using other technologies. WF provides a workflow engine that can be used to implement long-running processes.²