JavaScript Object Notation for Linked Data is an implementation format for structuring data analogous to Microdata and RDFa. Typically, in terms of SEO, JSON-LD is implemented leveraging the Schema.org vocabulary, a joint effort by Google, Bing, Yahoo!, and Yandex in 2011 to create a unified structured data vocabulary for the web.
JSON-LD is completely separate from the HTML code. One of the advantages of this lightweight Linked Data format is that it is easy for humans to read and write. JSON-LD transports Linked Data using the JavaScript Object Notation (JSON), an open standard format using human-readable text to transmit attribute-value pairs. If the JSON-LD code is written in a separate file rather than the markup, the de facto file extension is .jsonld. The Internet media type of JSON-LD is application/ld+json and, if written in the markup, the JSON-LD code is delimited by curly braces between the <script> and </script> tags.
Google recommends adding JSON-LD to the <head> section of the HTML document; however, it’s okay if the JSON-LD is within the <body> section. Google can also grasp dynamically generated tags in the DOM.
Listing 1. Compact JSON-LD Code in the Markup:
When you see JSON-LD, the first think you should always see is a <script> tag. The <script> tag with a type attribute says, “Hey browser, I’m calling the JavaScript that contains JSON-LD.” So...remember close every tag you open when you open it.
The second element that retains a permanent place in JSON-LD markup is the "@context" with the value of "http://schema.org". The @context says, “Hey browser, this is the vocabulary I’m referencing. You can find it at http://schema.org.”
When search engines crawl through your website’s content, they’re attempting to put it all into a specific context. For years, we have relied on good old fashioned HTML tags to tell a story. Titles, headings, meta descriptions and keywords have all had a role in how a search engine listed and ranked our website.
For instance, if your home page has a title of “Web Designer New York City”, a search engine may well assume that’s what your site is about. But things aren’t always that obvious. As often happens, words and phrases can have multiple meanings and contexts. Without knowing that kind of information for certain, your site could be losing out when it comes to search relevancy.
That’s where Schema markup comes in. Created in part by search behemoths Google, Microsoft, Yahoo and Yandex, Schema adds a behind-the-scenes “vocabulary” to our content. Adding this markup to specific parts of a website will provide search engines with a higher level of context.
Google makes it easy to determine your site’s markup with its Structured Data Testing Tool. Enter your site’s URL or paste in a code snippet to let the tool analyze your content.
An full example of template script of "LocalBusiness":
You can check all of reference of "localbusiness" on http://schema.org/LocalBusiness and other ones on http://schema.org/docs/full.html
Here are an incredible video showing more about JSON-LD. Check it out and have fun...
Thank you very much Thomas Bradley for you authorization! :)