To understand schema.org one has to consider Snippets and Rich Snippets. Snippets is nothing else than a few lines of Text that appear under every Search result and is designed to give User a Sense for what is on the Web Page and why it is relevant for the Query. The Snippet might give one some Context and Content. So one might get a clue what it is all about. If Google is able to understand the Content of Web Page it is able to create such a Snippet. To understand means that there is structured Data inside the HTML Page that can be read and understood. One can do this by using Schema.org. Schema.org defines nothin else than data that can be read by Search Engines and then be displayed in the Form of Rich Snippets.