A militia /mᵻˈlɪʃə/ generally is an army or other fighting unit that is composed of non-professional fighters, citizens of a nation or subjects of a state or government who can be called upon to enter a combat situation, as opposed to a professional force of regular, full-time military personnel, or historically, members of the warrior nobility class (e.g., knights or samurai). Unable to hold their own against properly trained and equipped professional forces, it is common for militias to engage in guerrilla warfare or defense instead of being used in open attacks and offensive actions.