An ExpertUser can be described as a DomainExpert who uses Computers and Computer Programs to accomplish tasks within the Expert's Domain. A user who knows what needs to be done and determines to use the capabilities of the computer to accomplish Project or Process Targets. This kind of user is not usually concerned so much with how something is accomplished within the computer as long as it is consistent and agreeable with what would be accomplished manually.
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After all, the interaction between the ExpertUser and the ExpertDeveloper is at the core of some of these emerging technologies, like AgileModeling and ExtremeProgramming.

Or is it because it is self-explanatory? -- PeterLynch

''The fast growing discussion about the similar/equivalent term "BusinessProfessionals" suggest that is is not self-explanatory. -- OriInbar'' 

Perhaps you could explain what is different between the two?  Some of the original discussion about BusinessProfessionals was asking what makes it different from ExpertUser.

* Well I thought it was self-explanatory. Obviously it depends where you are standing. I always understood an ExpertUser to be somebody who is expert in the user domain. Yet the definition above makes the ExpertUser an "Expert DIY Developer". As if there is no room for the ExpertDeveloper? As for the BusinessProfessionals term, anybody who participates in a career in business is a professional. I think "Things" would be just as descriptive of their role. 

''(and may I ask what is DIY?)''

* Forgive the AustralianCulturalAssumption - DIY = Do It Yourself -  building your own (system, house, shed, boat ...)


''"BusinessProfessionals" or "Non Programmer Developers" (NPD) is a more general term. Some of the NPD are gain their expertise not from the angle of users.  Moreover, the term: "Expert" is usually associated with a very profound knowledge in a very narrow field, "Professionals" or "Developers" are not as specific. The TgpMethodology want to give these people an equal status as programmers in the development process. Sometimes it is the "passion" of the developer and not her/his knowledge in the domain that can qualify them to take the role of NPDs rather than of programmers. -- OriInbar''

Which means that ExpertUsersAreDevelopers - at least in the Agile context. I guess we are talking of the same thing, only looking for a better name