Genetic algorithms, neural nets, cellular automata, robotics, molecular engineering, artificial intelligence.
"The discipline of building organisms and systems that would be considered alive if found in nature." --Marvin Minsky.
"After the 1987 conference [First Conference on Artificial Life] at Los Alamos, a consensus began to develop that to qualify as life artificial organisms must demonstrate four qualities. First, they must exhibit evolution by natural selection.... Second, they must possess a genetic program.... Third, they must demonstrate a high level of complexity.... The quality of complexity would lead to the fourth necessary quality: self-organization." --Sherry Turkle (in Life on the Screen , 1995).
"Artificial Life is a bottom up approach to creating Artificial Intelligence. Rather than trying to develop an artificial brain in its entirety, ALife attempts to breed cognitive software ala nature." --Henry W.Targowski (in Mark/Space , 1997).
"Simple programs that grow and get more interesting as time goes on. Programs that eat computational energy!" --Rudy Rucker (in "Report from Silicon Valley", Science Fiction Eye , August 1988).