If you hadn't noticed already over the past few days, Facebook has now introduced hashtags to its content.
Facebook wants users to expand the use of its site by doing what Twitter does and allow people to search for content based on hashtags. Hashtags are very popular on Twitter when it comes to events and Facebook want a piece of the pie.
When you click on an hashtag you'll be shown more content with that hashtag too, just like on Twitter, Instagram or Tumblr.
Facebook seems to be late to the party when it comes to hashtags but they can't ignore it anymore.
Weirdly though, I and many others still don't even have the new Facebook design and search functionality. We want this.