bandit

A bandit is a person who engages in robbery or extortion, typically operating in rural or border regions. The term is often associated with outlaws, raiders, or highwaymen. In common usage, bandit may describe individuals, groups, or organizations that commit theft by force or intimidation.

The word derives from Italian bandito, from Medieval Latin banditus, meaning outlaw or criminal. In Europe, banditry was a recognized social issue from the Middle Ages into the early modern period, with bands of robbers operating along roads and in mountainous areas.

Bandits appear in folklore, literature, and film as both antiheroes and villains. Their depictions vary from romanticized rebels against oppressive authorities to ruthless criminals. The term is also used as a nickname or alias in popular culture and sports.

In science and technology, the term appears in the concept of the multi-armed bandit problem, which models a decision maker choosing among several options with uncertain rewards to maximize cumulative payoff. Bandit algorithms, including epsilon-greedy, UCB (upper confidence bound), and Thompson sampling, are applied in online experimentation, advertising, recommender systems, and clinical trials to balance exploration and exploitation.

See also: highwayman, banditry, multi-armed bandit.