What is Schema.org?
Schema.org is a joint initiative by Google, Yahoo, Microsoft Bing and the Russian search engine Yandex, which was launched in June 2011. The aim of the initiative is to help search engines to interpret information on web pages so that it can be used to improve the display of search results, making it easier for people to find the information they are looking for.  To do this, content publishers insert machine readable information into the HTML of web pages that helps search engines understand the significance of the text on those pages.  This information helps to identify which text is the title, which is the authors name, which link is to the publisher, etc. In other words, it allows human readable resource descriptions to double up as machine readable metadata, or what Google calls structured data. 
Schema.org has two components: 
An ontology, i.e. a vocabulary for naming the types and characteristics of resources, their relationships with each other, and constraints on how to describe these characteristics and relationships.
The expression of this information in machine readable formats such as microdata, RDFa Lite and JSON-LD.
This Briefing follows the terminology used by schema.org microdata and refers to the resource being described as an item. The first step in describing an item is to classify it as a specific type of resource. This identifies what type of thing the item is, and for each type schema.org defines a set of properties that may be used to provide descriptions of the characteristics of the item. The schema.org documentation lists a hierarchical set of types and their properties. The top level of the hierarchy, the most generic type, is Thing, subtypes of this include CreativeWork, Event, Intangible, Organization, Person, Place and Product.  Subtypes that are of particular interest to education include ScholarlyArticle, Book, Review and WebPage (all subtypes of CreativeWork),  EducationEvent and EducationalOrganization (subtypes of Event and Organization respectively).  Each type in the hierarchy may have its own set of properties, but properties are also inherited from the parent type. The main properties of the generic Thing, which are inherited by all other types, are 
description (Text): a short description of the item
image (Url): URL of an image of the item
name (Text): the name of the item
url (Url): URL of the item
The text in parenthesis above indicates the expected type for the data provided about that property (in terms of RDF Schema it is the range of the predicate), that is, the description and name can be free text, whereas the others must be URLs.
So, the CreativeWork type inherits all the properties of Thing listed above and provides about forty more, including
about (Thing): the subject matter of the content
author (Person or Organization): the author of this content
dateCreated (Date): the date on which the CreativeWork was created
publisher (Organization): the publisher of the creative work
Note that, with the exception of date (which should be in ISO 8601 date format), the information about these properties should all be provided as embedded items of other schema.org types, an example is provided below. In fact schema.org is designed to be forgiving to the extent that if information about the author is provided as a plain text string, an attempt should be made to interpret it.
