In 1956, John McCarthy, an American computer scientist, referred to the terms “artificial intelligence” and “AI” as “the science and engineering of making intelligent machines.” The concept of AI has evolved significantly since then with increasing focus on what it means to describe a machine as “intelligent.”
Modern definitions of AI differ. Some focus on the ability of a program to make any form of predictions, recommendations, or decisions. For example, the NIST Artificial Intelligence Risk Management Framework defines an “AI System” broadly as any “machine-based system that can, for a given set of objectives, generate outputs such as predictions, recommendations, or decisions influencing real or virtual environments.” Other definitions more narrowly define the term to refer to programs that either approximate, or substitute for, human thinking. For example, one definition refers to the terms as “machines that respond to stimulation consistent with traditional responses from humans . . . .” In other words, programs that are capable of approximating humans.
 NIST AI RMF 1.0 at 1.
 Shukla Shubhendu et al, Applicability of Artificial Intelligence in Different Fields of Life, 1 Int’l J. of Scientific Engineering and Research 1 at 28 (Sept. 2013).