This book reviews creative technologies that underpin the human activities of converting data and information into knowledge, creating new ideas based on that knowledge, and validating those ideas. The book calls such creative technology "knowledge technology" and explores its challenges in the age of big data. Today, artificial intelligence and big data are successfully performing pattern recognition and decision making on behalf of humans, who are incapable of processing large amounts of information instantly and accurately. In using only past data, however, there are limits to future predictions with artificial intelligence and big data. Humans need to take the lead in predicting or creating the future by trying to understand why data emerged. Knowledge technology contributes to that understanding, regardless of the field of origin. As a matter of fact, knowledge technology includes many technologies developed in informatics, management study, and systems science. The desirable features of knowledge technology are the complementary use of rational and intuitive approaches, the integration of results from quantitative and qualitative analyses, and the cooperation between artificial intelligence and humans.