The expert system is considered to be a system that answers questions that normally people would call on a expect to answer. They are most commonly used in public domain, The main reason that expert systems are involved are because humans are never 100 percent confident with their answers. In order to be sure, expert systems had to be created to offset the difference. There are a couple of methods that the expert system uses to gather his results. The sequence of steps that it takes to gather these results changes with each new problem. They also have the ability to produce many values. Also, instead of applying different techniques to gain results, they apply specific knowledge's. This tells us that humans do not process their information and that they possess different knowledge.
Some of the advantages of the expert system include the fact that it provides consistent answers for repetitive decisions and tasks, it is also able to hold and maintain significant amounts of information and it it always remembers to asks the questions that we sometimes forget to.
The only disadvantage is that it is unable to change with the environment.