README.md in simpler_workflow-0.1.2 vs README.md in simpler_workflow-0.1.3

@@ -167,9 +167,20 @@
 You can also define similar hooks for events using the following methods:
 
 * ```on_activity_completed``` is called when an activity completes and SWF reports back to the decision loop.
 * ```on_activity_failed``` is called when an activity reports a failure to SWF.
 
+## Workflow and Activity Versioning
+
+All workflow types and activity types are versioned under SWF. This allows an organization to release new versions of a workflow or activity
+as they are updated and allow workflows to complete under the old version number if need be.
+
+Here are a few recommendations on when to change the version of a workflow or activity when using SimplerWorkflow:
+
+1. You need to bump the version when you are changing the defaults associated with an activity or workflow. These are set using the ```default_``` methods. The defaults are commnicated to AWS when the workflow or activity is registered. It does not get updated when they are changed within the code.
+2. You may want to bump a version if you have work in progress under an existing workflow and you need to introduce changes for new work. You will need to keep the older activity and or workflow around while it completes.
+3. You do not need to bump the version when you change the work performed by the activity or the decision loop itself. This is code that is directly managed by SimplerWorkflow and isn't communicated to AWS. This only works if you do not want previous workflows to finish using the previous version of the code though.
+
 ## Contributing
 
 We welcome all kinds of contributions. This include code, fixes, issues, documentation, tests... Here's how you can contribute:
 
 1. Fork it