Choosing a Data Format for SEO
You may have noticed two different coding methods that frequently show up when SEO is discussed; the first is the Microdata markup, and the second is something called microformats markup. There are other ways to mark up code: RDFa, JSON-LD, and Open Graph, a markup designed by Facebook to help it recognize data that it finds in web pages.
There are two different things to consider here: the vocabulary used, and the markup method used. For instance, schema.org publishes a vocabulary for hundreds of different “classes” or data types (most aren’t supported by the search engines, but who knows what the future brings). There are vocabularies for anything you can think of: video games, exercise plans, maps, sports events, bus trips, train reservations, and even for actions (such as the action of eating and the action of wearing).
For example, for an article placed into a web page, you can define the various elements of the article by using such terms as articleBody, articleSection, wordCount, author, and so on.
However, somehow you have to code your pages using this vocabulary — you have to mark up your data — and that can be done in various ways. A great way to see this in action is to spend some time digging around on schema.org, where you’ll find these hundreds of vocabularies. In many cases, you see examples of each one employed by using three formats: Microdata, RDFa, and JSON-LD.
So which data format do you use? Well, Google prefers JSON-LD; on the other hand, Google doesn’t currently support JSON-LD markup for all data types, so read Google’s latest information to figure out whether JSON-LD is supported for your data.
For data types with no JSON-LD, Google recommends Microdata or RDFa. They certainly used to support microformats, but seem to be recommending these other three formats right now.
Bing doesn’t seem to care. Currently, Bing states that “It’s entirely up to you to decide which of the supported specifications best fits your data.” However, it doesn’t appear to support JSON-LD. If you like, you can use JSON-LD for the data that Google prefers it; if it’s a component for which Bing also reads structured data markup, also use one of the Bing approved formats (there’s no reason you can’t use JSON-LD and microdata, for instance).