Facebook introduced Open Graph in 2010. It promotes integration between Facebook and other websites by allowing them to become rich “graph” objects with the same functionality as other Facebook objects.
Put simply, a degree of control is possible over how information travels from a third-party website to Facebook when a page is shared (or liked, etc.). In order to make this possible, information is sent via Open Graph meta tags in the head part of the website’s code.
Now, other social media sites also are taking advantage of social meta tags. All of the other major platforms, Twitter, LinkedIn, and Google+, recognize Open Graph tags. Twitter actually has its own meta tags for Twitter Cards, but if Twitter robots cannot find any, Twitter uses Open Graph tags instead.
To add Open Graph tags into your WordPress website, Upload and activate the following plugin;
After activating the plugin, you can go to plugin settings page and fill the required fields, select default images etc.
You may need to save your post/page to clear Facebook cache and view the final result.