In United States films of the Western genre between the 1920s and the 1940s, white hats were often worn by heroes and black hats by villains to symbolize the contrast in good versus evil. The 1903 short film The Great Train Robbery was the first to apply this convention. Two exceptions to the convention were portrayals by William Boyd (active 1918–1954), who wore dark clothing as Hopalong Cassidy, and Robert Taylor's portrayal in the film The Law and Jake Wade (1958). This convention gave rise to the terms white hat and black hat to refer to ethical and malicious hackers respectively.