This paper discusses the history of the instructional design and technology field in four major time periods: (1) 1900s-1930s, (2) World War II-1970s, (3) 1980s-1990s, and (4) 21st century. Since the 20th century has been discussed in detail in earlier works, this paper puts more focus on the 21st century section, which includes discussions of social media, online and blended learning, mobile learning, the open educational resource (OER) movement, massive open online courses (MOOCs), virtual reality (VR) and augmented reality (AR), digital game-based learning (DGBL), gamification, the maker movement, new instructional design process models, and instructional-design theory. While previous discussions of the history of the field focused on the history of instructional media and instructional design and the evolution of learning theories, this paper includes the discussion of the evolution of instructional-design theories and models, which have received relatively less attention.