Explanation modules, used in expert systems, is a function that enables the knowledge worker to understand why the information explained and concluded by the domain expert is viable. An expert system is Software that attempts to reproduce the performance of one or more human Experts most commonly in a specific Problem domain, and is Knowledge worker (also referred to as as intellectual worker or brain worker) is someone who is employed due to his or her knowledge of a subject matter rather than A domain expert or subject matter expert (SME is a person with special knowledge or skills in a particular area While consulting the information provided by the expert system, the explanation module elucidates why the expert system reached its conclusion. Explanation modules are mostly used in training seminars, as audiences are interested in learning how problems in the expert system are solved. Seminar is generally a form of Academic instruction either at a University or offered by a commercial or professional organization Brooklyn Book Festival crowd by David Shankbonejpg|thumb|An audience at the Brooklyn Book Festival in New York City.