These activities have been built by Windows Workflow Foundation, and are installed together with Studio. They provide functionality for control flow, conditions, event handling, state management, and communicating with applications and services.
Please note that in this guide we have only documented the essential Workflow Foundation activities. For more information please visit Microsoft's official documentation - https://msdn.microsoft.com/en-us/library/ms733615(v=vs.90).aspx.
Updated about a year ago