A running request of a workflow that contains a sequence of
action occurrences and/or activity model requests. These action and activity instances
can be sequenced in any order to build a single activity flow.
Tracked updates associated to an explicit user. These items
are often related to the user’s social collaboration within SharePoint (such as
tagging, rating, likes, etc.).
The tiniest component of work in a workflow system. An
action can comprise one or more responsibilities that define work that needs
done. Actions are deployed and registered in the workflow system to be triggered
by protocol users. Additionally, this is a component of work that can be
performed by a workflow and is usually defined in a workflow markup file.