The document summarizes the evolution of the horror genre from the 1920s to the present day. It discusses how the fears of audiences have changed over time and how the genre adapted films to reflect these new fears, such as scientists experiments in the 1950s reflecting fears of radiation. More recent horrors focus on psychological terrors and found footage films that make the scares feel more realistic. Overall, the genre has had to continually reinvent itself based on changing social fears and technologies to keep audiences engaged.