In addition to recent stories, the stream of stories from all of your subscribed friends and pages, Facebook also displays what it considers “highlighted stories” at the top of your News Feed.
Facebook tries to show the most relevant news since you last checked Facebook, which is based on a range of factors, including your relationship to the person who posted the story, how many comments and likes it has, the type of story and so on. A status update may not be of much interest until other people comment on it.<!--more-->
You can influence what is or isn’t considered a highlighted story by clicking the tab in the left corner of a post and marking or un-marking the story. This prompts Facebook to display more or fewer stories of that type at the top of the user’s News Feed.
You get a Sort by option at the top of your news feed which defaults to Top Stories overriding Most Recent, which is why your feed sometimes appears out of chronological order. Hover your mouse over the Sort By link and the options box will open up for you to select.
There is an interesting aspect of Top Stories that the Internet marketers love. You don't have to Like a page to interact with and influence its ranking. If your friend posts something from a Fan page, you can comment on it, Like it, and share it without becoming a fan of the page, but still drive that post up the Facebook rankings. RC