Facebook June 2010. After extensive testing and years of questions from the public about whether it had an intention to incorporate a "Dislike" button, Facebook officially rolled out "Reactions" to users worldwide on February 24, 2016, letting users long-press on the like button for an option to use one of five pre-defined emotions, including "Love", "Haha", "Wow", "Sad", or "Angry". Reactions were also extended to comments in May 2017. Facebook Messenger is an instant messaging service and software application. Originally developed as Facebook Chat in 2008, the company revamped its messaging service in 2010, and subsequently released standalone iOS and Android
Criticism of Facebook their behavior. For instance, in "A 61-Million-Person Experiment in Social Influence And Political Mobilization," during the 2010 elections, Facebook users were given the opportunity to "tell your friends you voted" by clicking on an "I voted" button. Users were 2% more likely to click the button if it was associated with friends who had already voted. Much more controversially, a 2014 study of "Emotional Contagion Through Social Networks" manipulated the balance of positive and negative messages seen by 689,000 Facebook users. The researchers concluded that they had found "some of the first experimental evidence to support the controversial claims that