The News Feed lets you view all of your Friends' updates in one place. However, if you have many Friends or even a few Friends who post every second. you might find that looking at your News Feed can be overwhelming. So Facebook has a way for you to control this flow of information.
Sorting Your News Feed There are two ways to sort the stories in your News Feed. You can view the most recent stories first, or the most important stories first. In this case, "most important" means Top Stories, which
are the stories Facebook thinks you'll find the most interesting.
What makes a something a top story is based on several different things, including your relationship to the
poster, the type of story it is, and how many comments and likes it's received.
To Sort Your News Feed: At the top of your News Feed, click Sort.
"Facebook Tips: Managing News Feed "
Reference : facebook101tipstricks.com