The history of horror films is one that was described by author Siegbert Solomon Prawer as difficult to read as a linear historical path, with the genre changing throughout the decades, based on the state of cinema, audience tastes and contemporary world events. Films prior to the 1930s have been retrospectively described as horror films as the genre did not become a codified genre until the release of Dracula (1931), where the style and themes of the film have been specifically re-adapted into similar works.