Schema.org (often called Schema) is a semantic vocabulary of tags (or microdata) used to help search engines provide users better search results. Schema can be added to the HTML of your website design to improve your pages in SERPs.
Schema.org is possible thanks to a collaboration which includes companies like Google, Bing, Yandex, and Yahoo! The main goal is to create a criteria that search engines can use to understand websites better. This in turn allows these search engines to provide relevant searches for the users. By adding Schema markups to your HTML (and thus enhancing the snippets beneath your page title), you are ensuring a better chance of your webpage displaying in SERPs.
Let’s take a look at the two examples above. The first contains a publication date and star rating, which are becoming more important for business credibility and can both be added using Schema. On the other hand, the second search result lacks these rich snippets and therefore displays the information Google could find. To get the review rich snippet, you would use the following code:
Don’t forget that you can use Google's Structured Data Markup Helper to generate your own code.
It is true that structured data and microdata both pair a name with a value to help search engines index and categorize a website’s content. However, microdata is a specialized version of structured data that works with HTML5. Schema.org is different in that it is a collaboration project that seeks to provide definitions for microdata tags.
Does Schema replace Open Graph?
Schema and Open Graph are two distinct things, and although they can be used together, Open Graph does not replace Schema. Facebook uses Open Graph (a type of markup) to parse out which information to display. Another distinction is that Schema provides a more detailed list of options for SEO.
Types of items described by Schema
Although structured data can be used to mark up all kinds of items (like products, recipes and events), it is most often used to provide additional information about the following:
It is important to use every relevant property to describe your product. For example, a "book" may fall under the category of "creative work," but it can be described with properties such as "name" (title), "author," "illustrator," "isbn," and any other property that might help set it apart.
Another example can be an “event,” which can be classified as a "businessevent," "theaterevent," or anything that highlights what type of event it is.
Schema is recognized and maintained by Google, Bing, Yahoo!, and Yandex. Other search engines might use Schema markups for their SERPs, but that is not clear at the moment.
The effect that structured data has on page rankings has been discussed and experimented extensively. However, there is no conclusive evidence that this markup improves rankings. That’s not to say they do not help. There is reason to believe that search results with more extensive rich snippets (like those created using Schema) have a better click-through rate. It does not hurt to experiment with Schema markups and see how these rich snippets affect the client responses.
Using Schema with other structured data
Schema can be used with RDFa and JSON-LD, but it is not supported by microformats.