a subject-matter expert (sme) or domain expert is a person who is an authority in a particular area or topic. the term "domain expert" is frequently used in expert systems software development, and there the term always refers to the domain other than the software domain. a domain expert is a person with special knowledge or skills in a particular area of endeavour (e.g. an accountant is an expert in the domain of accountancy). the development of accounting software requires knowledge in two different domains: accounting and software. some of the development workers may be experts in one domain and not the other.