Expert systems are technology-based tools that help to solve problems.
Knowledge engineering is the process of capturing intelligence from human experts so that it can be used by the expert system for its reasoning. Human itelligence is put into an artificial machine to make the system an expert in a specific domain.
Of course, this intelligent machine isn’t the same as the human expert. The machine can’t actually think for itself. The systems I work on only know to follow a specific set of rules to put the human itelligence into action. But they can still reason in their own way.
The end result is a system that can emulate human reasoning and makes expert knowledge and guidance available to non-experts. Having a machine provide this reasoning helps us to address scarcity problems like a lack of experts or a lack of resources to pay for experts.
The expert who puts her knowledge into the system can then share her expertise with many non-experts all at once, even when that expert is actually working on another interesting problem – especially one that’s unsuitable for expert systems. Or, the expert can just spend time with her family on a beach.