The history of training and development began with apprenticeship programs before the 1800s. In the 1800s, companies began establishing factory schools to train workers for new industrial jobs. In the late 1800s, sales training programs and vestibule training were introduced. Scientific management methods were developed in the early 1900s to improve productivity. During World Wars I and II, specialized training programs were developed to meet increased wartime labor demands. After World War II, individualized instruction and computer-based training grew in use. Instructional system design and blended learning models emerged from the 1950s onward, followed by elearning, mobile learning, social learning, and other modern training trends in the late 20th century.