Featured Pictures will be the main picture that will pop along the link, whenever we share any of our Posts on Social Media Websites like Facebook, Twitter, LinkedIn etc.
For example on Facebook, it looks like this :
Select the picture that you think justifies or best explains the post in one picture. When you upload that picture into your post, as explained in How to Upload and Add Pictures to Posts, also add the same picture link to the field Featured Picture URL, thats it!
Rest our intelligent system will handle.
If you don't then Facebook or any other social media website, will simply show the URL with a small description and Title, which looks sad. Also, when a good picture comes up along with a shared URL, it increases the probability of other users clicking on the link and share it as well.