From the post:
When we launched schema.org almost 3 years ago, our main focus was on providing vocabularies for describing entities — people, places, movies, restaurants, … But the Web is not just about static descriptions of entities. It is about taking action on these entities — from making a reservation to watching a movie to commenting on a post.
Today, we are excited to start the next chapter of schema.org and structured data on the Web by introducing vocabulary that enables websites to describe the actions they enable and how these actions can be invoked.
The new actions vocabulary is the result of over two years of intense collaboration and debate amongst the schema.org partners and the larger Web community. Many thanks to all those who participated in these discussions, in particular to members of the Web Schemas and Hydra groups at W3C. We are hopeful that these additions to schema.org will help unleash new categories of applications.
From http://schema.org/Action:
Thing > Action
An action performed by a direct agent and indirect participants upon a direct object. Optionally happens at a location with the help of an inanimate instrument. The execution of the action may produce a result. Specific action sub-type documentation specifies the exact expectation of each argument/role.
Fairly coarse but I can see how it would be useful.
BTW, the examples are only available in JSON-LD. Just in case you were wondering.
Given the coarseness of schema.org and its success, due consideration should be given to semantics of “appropriate” coarseness for any particular task.