A fist bump is a friendly gesture exchanged between individuals, much like a handshake or a high five, in which two people bump their closed fists together at the knuckles. Any number of occasions can be cause for a fist bump, from encountering an old friend to celebrating a victory, and the fist bump may also be combined in another form of physical greeting. The fist bump is also known as a fist pound, bump, or knuckle bump, among other things.

Among the wide library of physical greetings used by humans all over the world, the fist bump is a bit unusual, as it involves a closed fist. In most societies, a closed hand is perceived as hostile or confrontational, rather than friendly, and this can lead to some misinterpretation of the fist bump among people who are not familiar with the gesture.

The origins of the fist bump are a bit unclear. Historical evidence suggests that it may be related to the dap greetings exchanged by soldiers in African-American units during the Second World War and Vietnam. The dap greeting is a form of complex greeting which may take a few seconds to a few minutes, depending on the style of greeting being used, and such greetings typically include a complex embedded social code which identifies the people involved in the greeting to each other, much like a Masonic handshake. Over time, the dap greeting came to be associated with black solidarity, with various versions reflecting membership in organizations, communities, and political groups. Certainly by the 1970s, the fist bump was common in sports, and many people were familiar with the mechanics of the dap greeting.

Although most common in the black community, the fist bump also appears among other racial groups as well. Many subcultures develop their own version of a dap greeting, which often integrates a fist bump along with other gestures which may include slapping or clapping the hands. For people who belong to such communities, the fist bump is a source of connection with other members of the community, and it may become so reflexive that they aren't even conscious of performing a dap greeting.

The world at large became especially interested in the fist bump in 2008, when U.S. Democratic Presidential hopeful Barack Obama exchanged a fist bump at the podium with his wife, Michelle. The resulting media frenzy over the affectionate gesture came as a surprise to the candidate, who simply commented that sometimes he and his wife like to do “silly things” together. As a celebratory gesture, the fist bump was quite appropriate for the moment, and perhaps more enjoyable for American voters to view on television than some of the more extravagant displays of affection between candidates and their spouses.