Facebook has made an attempt to boil down the human experience into five "Reactions". More accurately, they have expanded their "Like" feature (to engage with a post) into Like plus 5 other different emojis. An emoji is one of those little carton faces or images - like the "smiley face".
So, instead of just "Liking" a Facebook post you can chose from Like, Love, Haha, Yay, Wow, Sad or Angry.
HNGNAs to where the much asked for “dislike” button is, Facebook Founder, Chairman and Chief Executive Officer Mark Zuckerberg said on his Facebook page that he wanted to “keep the experience simple and respectful.”