Imagine a piece of equipment that could solve all your problems, give you advice and deliver conclusions to your questions, and bring you closer to the knowledge you are seeking. It would not only propel your mind to the limits of its dimensions, but also try to break the barriers holding that dimension. What kind of a brilliant machine would this be? Is this kind of machine possible in this day and age? What will be the requirements in making this machine? Yes, this machine does exist and it is called Expert systems.

A regular definition of Expert System is a "knowledge-based system that emulates expert thought to solve significant problems in a particular domain of expertise."(Sell pg. 15) To put it in simple words, an Expert is a person who has complete knowledge in a certain domain of expertise or gets its knowledge through the knowledge acquisition process. The Expert then implements that knowledge into a system. So the system has a limit on its expertise at the level of the Expert, who is the creator of the system. The Expert is the person who guides the system to perform certain tasks to help the user.

There are some characteristics that an Expert System does or doesn’t do. Firstly, Expert System must perform well on difficult problems. Secondly, it is not reasonable to expect better performance from an Expert System than from an Expert. If the Expert has implemented his system on a computer, we can expect it to be available and fully functional for 24 hours a day, not get tired of working. Thirdly, the expert system answers all the questions it is implemented to answer. But we cannot rightfully expect that all its answers will always be correct. The Expert System only performs at the performance of expert’s implementation. Finally, Expert Systems are usually designed to interact with human beings. The Expert System asks questions and then renders advice on your answers. To do this effectively, the system must converse in terms that the user can understand and in terms relevant to the problem at hand.

Expert system must be able to explain itself, particularly in three respects. First of all, and most important, a system must be able to explain how it reached its conclusion from the facts given. Then the user can either correct its judgement from the conclusion or reject that of the system. Second, the system must justify why it needs a particular piece of information. It should let the user know if the information required is costly or – as can arise in a medical system – requires invasive or painful tests. The third requirement is the ability on the part of the system to explain why it has not reached a particular conclusion.

Expert systems are like a work of art; they are never finished only abandoned. They will be abandoned promptly if there is no easy way to modify the knowledge. Both our knowledge and expectation of the system change according to time. If the system can’t accommodate with this change, then the system is abandoned. Expert systems help us answer many questions, but these systems must also be up to date. The future relies on these systems to keep us up to date on future technologies, personal questions, and help us better understand by giving us advice on certain areas in which we may not be so expert in.