Artificial Intelligence has long been considered as fruit of our intentions to realize nature in our mechanized- human lives; just as aero planes were, of our desire to fly with like the birds of flight. Case-based reasoning (CBR), is the process of solving new problems based on the solutions of similar past problems. An auto mechanic who fixes an engine by recalling another car that exhibited similar symptoms is using case-based reasoning. A lawyer who advocates a particular outcome in a trial based on legal precedents or a judge who creates case law is using case-based reasoning. Case-based reasoning is a prominent kind of analogy making. It has been argued that case-based reasoning is not only a powerful method for computer reasoning, but also a pervasive behavior in everyday human problem solving. Or, more radically, that all reasoning is based on past cases experienced or accepted by the being actively exercising choice “ prototype theory “ most deeply explored in human cognitive science. CBR technology has produced a number of successful deployed systems, the earliest being Lockheed s CLAVIER, a system for laying out composite parts to be baked in an idustrial convection oven. CBR has been used extensively in help-desk applications such as the Compaq SMART system. As of this writing, a number of CBR decision support tools are commercially available, including k-Commerce from eGain (formerly Inference Corporation), Kaidara Advisor from Kaidara (formerly AcknoSoft) and SMART from Illation.