The thriller genre evolved from early crime films, using techniques like building tension from threats of violence. Alfred Hitchcock's 1926 film "The Lodger" is considered the first true thriller, establishing conventions like tension, surprise, and an intelligent storyline. Some common thriller subgenres are psychological thrillers, mystery thrillers, supernatural thrillers, action thrillers, and conspiracy thrillers. Thrillers typically target 18+ audiences due to violent or disturbing psychological content.