diff --git a/docs/flow.rst b/docs/flow.rst
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--- a/docs/flow.rst
+++ b/docs/flow.rst
@@ -1,6 +1,46 @@
 Flow extension
 ==============
 
+*Flow* in the context of Tapeti is inspired by what is referred to as a Saga or Conversation in messaging. It enables a controller to communicate with other services, temporarily yielding it's execution while waiting for a response. When the response arrives the controller will resume, retaining the original state of it's public fields.
+
+This process is fully asynchronous, the service initiating the flow can be restarted and the flow will continue when the service is back up (assuming the queues are durable and a persistent flow state store is used).
+
+
+Request - response pattern
+--------------------------
+Tapeti implements the request - response pattern by allowing a message handler method to simply return the response message. Tapeti Flow expands on this idea by enforcing you to explicitly declare that pattern. This is intended to prevent bugs where a flow will forever wait on a response that never comes.
+
+Due to this requirement your messages need to follow a pattern where broadcasts (events) are separated from true request - response messages (where the reply is sent directly to the originator).
+
+This may result in a message having two versions; one where a reply is expected and one where it's not. This is not considered a design flaw but a clear contract between services. An example is given in `Request - response versus transfer of responsibility`_.
+
+Declaring request - response messages
+-------------------------------------
+A message must be annotated with the Request attribute, where the Response property declares the expected response message class.
+
+::
+
+  [Request(Response = RabbitCountResponseMessage)]
+  public class RabbitCountRequestMessage
+  {
+      public int? MinimumAge { get; set; }
+  }
+
+  public class RabbitCountResponseMessage
+  {
+      public int Count { get; set; }
+  }
+
+
+Starting a flow
+---------------
+
+Ending a flow
+-------------
+
+Request - response versus transfer of responsibility
+----------------------------------------------------
+
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