For the longest time, people have been asking Facebook to incorporate some sort of dislike button into the service, but these requests were never met. People want the dislike button for one of two reasons, to show that they care by disliking sad posts or to be able to dislike someone's post that they are not too fond of. Basically, people want the dislike button to either show sympathy or hate towards a post and now it looks like Mark Zuckerberg is finally going to give them that capability.
Today during a Facebook "town hall" meeting, Zuckerberg announced that the Facebook team has been listening to all of the requests for a dislike button and that they are finally ready to do something about it. Yes, Zuckerberg just announced that a dislike button is actually being worked on and will be built into Facebook sometime in the near future. As a matter of fact, the dislike button that Facebook is currently working on will be heading into the testing phase soon.
The impending addition of a dislike button in Facebook can turn out to be either a great thing or a terrible thing, it's going to depend greatly on how people decide to use it. If a majority of people end up being jerks by disliking friends and families posts left and right, the dislike button can lead to some issues. Also, a big question pertaining to this is sponsored posts, will they have dislike buttons as well? Facebook nor the company paying for sponsored posts wants a ton of dislikes on a post that was paid for. People need to use the dislike button for the one reason that Zuckerberg said it is being designed for, "to express empathy." Hence, disliking a post pertaining to trauma or tragedy. Unfortunately, not much else besides the fact that the dislike button is coming is known about it right now. When and how it will be incorporated are two big questions that everyone is waiting to hear and with the feature already getting ready to head into testing, those questions may be answered sooner than later.