Since its invention, photography has proven one of the most effective means of reporting on major world events. However, Pierre-Jean Amar demonstrates that the transition from documentary photography to photojournalism was a slow process, occurring only after the First World War. Thus, from a simple illustration, photography became a true journalistic testimony, a narrative, a worldview of a subjectivity that represents the vision of a subject: the photojournalist. Images began to be used as a means of struggle to defend ideas and serve a cause. Amar warns of the danger that this commitment can transform into propaganda. This is where the tension, the counterpoint, between committed journalism and corporatism is generated. Some of the great names in the discipline are Robert Capa, Henri Cartier-Bresson, William Eugene Smith, Diane Arbus, and Bruce Davidson; and its distinctive component, de-automatization. According to Smith: "Some photos arouse such emotion that they trigger reflection." Undoubtedly, this is a key element for photojournalism to open up to the world and embrace its objective.