Facebook provides users with data for those that manage Pages, so literary magazines revealing their latest issue's table of contents, artists promoting new work or pun-loving helmsmen can track the reach of their posts to determine how their content is seen and shared on the social network.
Facebook Page Insights
Administrators can evaluate how fans (those who have liked your Page) interact with Pages under the "Insights" tab. It contains data such as like history, how many users share content, how many visit a Page, post popularity and fan demographics. This information can be used to see when fans are online, which type of post is shared more than others and if your audience is engaged.