What is the Google Structured Data Testing Tool used for?

At first glance, this may seem like a basic tool that helps you test your structured data and provides you with useful feedback, in addition to checking that your code is properly implemented. It can be used to validate JSON-LD, Microdata and RDFa formats while administering schemas on your website.
The best feature of this tool is that it can evaluate the data to help you identify segments of your audience that your page would be suitable for, thus giving you a targeted niche market to tap into.